实现画布控件背景颜色拾取和剪裁画布功能

- 画布控件创建canvasBitmap保存背景和图片
- 剪裁时剪裁画布控件而非原图片
- 添加颜色拾取按钮和功能
- 可从图片中拾取颜色设置为背景

gallery/src/main/java/cc/winboll/studio/gallery/CropActivity.java

@@ -0,0 +1,170 @@
+package cc.winboll.studio.gallery;
+
+import android.graphics.Bitmap;
+import android.graphics.BitmapFactory;
+import android.graphics.RectF;
+import android.net.Uri;
+import android.os.Bundle;
+import android.provider.MediaStore;
+import android.view.View;
+import android.widget.ImageView;
+import android.widget.Toast;
+import androidx.appcompat.app.AppCompatActivity;
+import cc.winboll.studio.libappbase.LogUtils;
+import java.io.File;
+import java.io.FileOutputStream;
+
+public class CropActivity extends AppCompatActivity {
+    public static final String TAG = "CropActivity";
+    public static final String EXTRA_IMAGE_URI = "image_uri";
+    public static final String EXTRA_IMAGE_PATH = "image_path";
+    public static final String EXTRA_ALBUM_PATH = "album_path";
+    public static final String EXTRA_CROP_WIDTH = "crop_width";
+    public static final String EXTRA_CROP_HEIGHT = "crop_height";
+    
+    private CropCanvasView cropCanvasView;
+    private Bitmap originalBitmap;
+    private String imagePath;
+    private String albumPath;
+    private int cropWidth = 240;
+    private int cropHeight = 120;
+    private float cropRatio = 2.0f;
+    
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_crop);
+        
+        imagePath = getIntent().getStringExtra(EXTRA_IMAGE_PATH);
+        albumPath = getIntent().getStringExtra(EXTRA_ALBUM_PATH);
+        cropWidth = getIntent().getIntExtra(EXTRA_CROP_WIDTH, 240);
+        cropHeight = getIntent().getIntExtra(EXTRA_CROP_HEIGHT, 120);
+        
+        Preferences prefs = new Preferences(this);
+        if (cropWidth > 0 && cropHeight > 0) {
+            cropRatio = (float) cropWidth / cropHeight;
+        } else {
+            cropRatio = prefs.getCoverRatio();
+            cropWidth = (int) (120 * cropRatio);
+            cropHeight = 120;
+        }
+        
+        findViewById(R.id.btn_close).setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                finish();
+            }
+        });
+        
+        final ImageView btnColorPick = findViewById(R.id.btn_color_pick);
+        btnColorPick.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                boolean pickMode = !cropCanvasView.isColorPickMode();
+                cropCanvasView.setColorPickMode(pickMode);
+                btnColorPick.setAlpha(pickMode ? 0.5f : 1.0f);
+            }
+        });
+        
+        findViewById(R.id.btn_done).setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                saveCroppedCover();
+            }
+        });
+        
+        cropCanvasView = findViewById(R.id.crop_canvas_view);
+        loadImage();
+    }
+    
+    private void loadImage() {
+        try {
+            if (imagePath != null && new File(imagePath).exists()) {
+                originalBitmap = BitmapFactory.decodeFile(imagePath);
+            } else {
+                Uri imageUri = getIntent().getParcelableExtra(EXTRA_IMAGE_URI);
+                if (imageUri != null) {
+                    originalBitmap = MediaStore.Images.Media.getBitmap(getContentResolver(), imageUri);
+                }
+            }
+            
+            if (originalBitmap != null) {
+                cropCanvasView.setImageBitmap(originalBitmap);
+                cropCanvasView.post(new Runnable() {
+                    @Override
+                    public void run() {
+                        initCrop();
+                    }
+                });
+            } else {
+                Toast.makeText(this, "Failed to load image", Toast.LENGTH_SHORT).show();
+                finish();
+            }
+        } catch (Exception e) {
+            LogUtils.e(TAG, "loadImage error: " + e.getMessage());
+            Toast.makeText(this, "Failed to load image", Toast.LENGTH_SHORT).show();
+            finish();
+        }
+    }
+    
+    private void initCrop() {
+        cropCanvasView.initCanvas(originalBitmap.getWidth(), originalBitmap.getHeight(), cropRatio);
+        
+        int viewW = cropCanvasView.getWidth();
+        int viewH = cropCanvasView.getHeight();
+        if (viewW > 0 && viewH > 0) {
+            cropCanvasView.scaleToView(viewW, viewH);
+        }
+    }
+    
+    private void saveCroppedCover() {
+        Bitmap canvasBitmap = cropCanvasView.getCanvasBitmap();
+        if (canvasBitmap == null) {
+            Toast.makeText(this, "Failed to get image", Toast.LENGTH_SHORT).show();
+            return;
+        }
+        
+        try {
+            RectF cropRect = cropCanvasView.getCropRect();
+            
+            int cropX = (int) cropRect.left;
+            int cropY = (int) cropRect.top;
+            int cropW = (int) cropRect.width();
+            int cropH = (int) cropRect.height();
+            
+            cropX = Math.max(0, Math.min(cropX, canvasBitmap.getWidth() - 1));
+            cropY = Math.max(0, Math.min(cropY, canvasBitmap.getHeight() - 1));
+            cropW = Math.max(1, Math.min(cropW, canvasBitmap.getWidth() - cropX));
+            cropH = Math.max(1, Math.min(cropH, canvasBitmap.getHeight() - cropY));
+            
+            Bitmap cropped = Bitmap.createBitmap(canvasBitmap, cropX, cropY, cropW, cropH);
+            
+            File cacheDir = getCacheDir();
+            File coverFile = new File(cacheDir, "cover_" + System.currentTimeMillis() + ".png");
+            FileOutputStream fos = new FileOutputStream(coverFile);
+            cropped.compress(Bitmap.CompressFormat.PNG, 100, fos);
+            fos.close();
+            
+            cropped.recycle();
+            
+            AlbumCoverDbHelper coverDbHelper = AlbumCoverDbHelper.getInstance(this);
+            coverDbHelper.setCoverWithCrop(albumPath, imagePath, coverFile.getAbsolutePath());
+            
+            Toast.makeText(this, "封面已保存", Toast.LENGTH_SHORT).show();
+            setResult(RESULT_OK);
+            finish();
+        } catch (Exception e) {
+            LogUtils.e(TAG, "saveCroppedCover error: " + e.getMessage());
+            Toast.makeText(this, "Failed to save cover", Toast.LENGTH_SHORT).show();
+        }
+    }
+    
+    @Override
+    protected void onDestroy() {
+        super.onDestroy();
+        if (originalBitmap != null) {
+            originalBitmap.recycle();
+            originalBitmap = null;
+        }
+    }
+}

gallery/src/main/java/cc/winboll/studio/gallery/CropCanvasView.java

@@ -0,0 +1,400 @@
+package cc.winboll.studio.gallery;
+
+import android.content.Context;
+import android.graphics.Bitmap;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Paint;
+import android.graphics.RectF;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import android.view.View;
+
+public class CropCanvasView extends View {
+    private Paint imagePaint;
+    private Paint borderPaint;
+    private Paint cornerPaint;
+    private RectF cropRect;
+    private int touchArea = 50;
+    
+    private float lastX, lastY;
+    private int activeCorner = -1;
+    private static final int CORNER_TOP_LEFT = 0;
+    private static final int CORNER_TOP_RIGHT = 1;
+    private static final int CORNER_BOTTOM_LEFT = 2;
+    private static final int CORNER_BOTTOM_RIGHT = 3;
+    private static final int CORNER_CENTER = 4;
+    
+    private int imageWidth;
+    private int imageHeight;
+    private float coverRatio = 2.0f;
+    
+    private int extendHeight;
+    private int extendWidth;
+    private int canvasWidth;
+    private int canvasHeight;
+    private float minSize = 50;
+    
+    private RectF imageBounds = new RectF();
+    private RectF canvasBounds = new RectF();
+    private Bitmap originalBitmap;
+    private Bitmap canvasBitmap;
+    private float initialSpan;
+    private int backgroundColor = Color.GREEN;
+    private boolean colorPickMode = false;
+    private float pickX, pickY;
+    
+    public CropCanvasView(Context context) {
+        super(context);
+        init();
+    }
+    
+    public CropCanvasView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        init();
+    }
+    
+    public CropCanvasView(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+        init();
+    }
+    
+    private void init() {
+        imagePaint = new Paint();
+        imagePaint.setFilterBitmap(true);
+        
+        borderPaint = new Paint();
+        borderPaint.setColor(Color.parseColor("#CCAA00"));
+        borderPaint.setStyle(Paint.Style.STROKE);
+        borderPaint.setStrokeWidth(3);
+        
+        cornerPaint = new Paint();
+        cornerPaint.setColor(Color.WHITE);
+        cornerPaint.setStyle(Paint.Style.FILL);
+    }
+    
+    public void setImageBitmap(Bitmap bitmap) {
+        this.originalBitmap = bitmap;
+    }
+    
+    public void initCanvas(int imgWidth, int imgHeight, float ratio) {
+        this.imageWidth = imgWidth;
+        this.imageHeight = imgHeight;
+        this.coverRatio = ratio;
+        
+        float imgRatio = (float) imgWidth / imgHeight;
+        
+        if (coverRatio >= imgRatio) {
+            extendHeight = imgHeight;
+            extendWidth = (int) (imgHeight * coverRatio);
+        } else {
+            extendWidth = imgWidth;
+            extendHeight = (int) (imgWidth / coverRatio);
+        }
+        
+        canvasHeight = Math.max(imageHeight, extendHeight);
+        canvasWidth = Math.max(imageWidth, extendWidth);
+        
+        float left = (canvasWidth - imageWidth) / 2f;
+        float top = (canvasHeight - imageHeight) / 2f;
+        imageBounds.set(left, top, left + imageWidth, top + imageHeight);
+        canvasBounds.set(0, 0, canvasWidth, canvasHeight);
+        
+        cropRect = new RectF(0, 0, canvasWidth, canvasHeight);
+        
+        createCanvasBitmap();
+        
+        requestLayout();
+        invalidate();
+    }
+    
+    private void createCanvasBitmap() {
+        if (canvasBitmap != null) {
+            canvasBitmap.recycle();
+        }
+        canvasBitmap = Bitmap.createBitmap(canvasWidth, canvasHeight, Bitmap.Config.ARGB_8888);
+        android.graphics.Canvas canvas = new android.graphics.Canvas(canvasBitmap);
+        canvas.drawColor(backgroundColor);
+        if (originalBitmap != null && !originalBitmap.isRecycled()) {
+            canvas.drawBitmap(originalBitmap, imageBounds.left, imageBounds.top, imagePaint);
+        }
+    }
+    
+    public Bitmap getCanvasBitmap() {
+        return canvasBitmap;
+    }
+    
+    public void setBackgroundColor(int color) {
+        this.backgroundColor = color;
+        createCanvasBitmap();
+        invalidate();
+    }
+    
+    public int getBackgroundColor() {
+        return backgroundColor;
+    }
+    
+    public void setColorPickMode(boolean enable) {
+        this.colorPickMode = enable;
+        if (enable) {
+            pickX = -1;
+            pickY = -1;
+        }
+        invalidate();
+    }
+    
+    public boolean isColorPickMode() {
+        return colorPickMode;
+    }
+    
+    public void scaleToView(int viewWidth, int viewHeight) {
+        if (viewWidth > 0 && viewHeight > 0 && canvasWidth > 0 && canvasHeight > 0) {
+            float scale = Math.max((float) viewWidth / canvasWidth, (float) viewHeight / canvasHeight);
+            int oldCanvasW = canvasWidth;
+            int oldCanvasH = canvasHeight;
+            canvasWidth = (int) (canvasWidth * scale);
+            canvasHeight = (int) (canvasHeight * scale);
+            
+            float left = (canvasWidth - imageWidth) / 2f;
+            float top = (canvasHeight - imageHeight) / 2f;
+            imageBounds.set(left, top, left + imageWidth, top + imageHeight);
+            canvasBounds.set(0, 0, canvasWidth, canvasHeight);
+            
+            if (cropRect != null) {
+                float scaleX = (float) canvasWidth / oldCanvasW;
+                float scaleY = (float) canvasHeight / oldCanvasH;
+                cropRect.left *= scaleX;
+                cropRect.top *= scaleY;
+                cropRect.right *= scaleX;
+                cropRect.bottom *= scaleY;
+            }
+            
+            requestLayout();
+            invalidate();
+        }
+    }
+    
+    public RectF getCropRect() {
+        return new RectF(cropRect);
+    }
+    
+    public int getCanvasWidth() {
+        return canvasWidth;
+    }
+    
+    public int getCanvasHeight() {
+        return canvasHeight;
+    }
+    
+    public RectF getCanvasBounds() {
+        return new RectF(canvasBounds);
+    }
+    
+    public RectF getImageBounds() {
+        return new RectF(imageBounds);
+    }
+    
+    @Override
+    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+        int w = canvasWidth > 0 ? canvasWidth : 0;
+        int h = canvasHeight > 0 ? canvasHeight : 0;
+        setMeasuredDimension(w, h);
+    }
+    
+    @Override
+    protected void onDraw(Canvas canvas) {
+        super.onDraw(canvas);
+        
+        if (canvasBitmap != null && !canvasBitmap.isRecycled()) {
+            canvas.drawBitmap(canvasBitmap, 0, 0, null);
+        }
+        
+        if (cropRect != null) {
+            canvas.drawRect(cropRect, borderPaint);
+            
+            canvas.drawCircle(cropRect.left, cropRect.top, 12, cornerPaint);
+            canvas.drawCircle(cropRect.right, cropRect.top, 12, cornerPaint);
+            canvas.drawCircle(cropRect.left, cropRect.bottom, 12, cornerPaint);
+            canvas.drawCircle(cropRect.right, cropRect.bottom, 12, cornerPaint);
+        }
+    }
+    
+    @Override
+    public boolean onTouchEvent(MotionEvent event) {
+        if (cropRect == null || canvasBounds.isEmpty()) return super.onTouchEvent(event);
+        
+        if (event.getPointerCount() == 2) {
+            int action = event.getActionMasked();
+            if (action == MotionEvent.ACTION_POINTER_DOWN) {
+                initialSpan = getSpan(event);
+                return true;
+            } else if (action == MotionEvent.ACTION_MOVE) {
+                float span = getSpan(event);
+                if (initialSpan > 0) {
+                    float scale = span / initialSpan;
+                    float centerX = cropRect.centerX();
+                    float centerY = cropRect.centerY();
+                    float newWidth = cropRect.width() * scale;
+                    float newHeight = newWidth / coverRatio;
+                    
+                    newWidth = Math.max(minSize, Math.min(newWidth, canvasBounds.width()));
+                    newHeight = newWidth / coverRatio;
+                    
+                    cropRect.set(centerX - newWidth / 2, centerY - newHeight / 2,
+                               centerX + newWidth / 2, centerY + newHeight / 2);
+                    
+                    initialSpan = span;
+                    invalidate();
+                }
+                return true;
+            }
+        }
+        
+        float x = event.getX();
+        float y = event.getY();
+        
+        if (colorPickMode) {
+            if (event.getAction() == MotionEvent.ACTION_DOWN) {
+                pickX = x;
+                pickY = y;
+                int color = getColorAt(x, y);
+                setBackgroundColor(color);
+                return true;
+            }
+            return true;
+        }
+        
+        switch (event.getAction()) {
+            case MotionEvent.ACTION_DOWN:
+                lastX = x;
+                lastY = y;
+                activeCorner = getActiveCorner(x, y);
+                return true;
+                
+            case MotionEvent.ACTION_MOVE:
+                float dx = x - lastX;
+                float dy = y - lastY;
+                
+                if (activeCorner == CORNER_CENTER) {
+                    float newLeft = cropRect.left + dx;
+                    float newTop = cropRect.top + dy;
+                    float newRight = cropRect.right + dx;
+                    float newBottom = cropRect.bottom + dy;
+                    
+                    if (newLeft >= canvasBounds.left && newRight <= canvasBounds.right) {
+                        cropRect.left = newLeft;
+                        cropRect.right = newRight;
+                    }
+                    if (newTop >= canvasBounds.top && newBottom <= canvasBounds.bottom) {
+                        cropRect.top = newTop;
+                        cropRect.bottom = newBottom;
+                    }
+                } else if (activeCorner == CORNER_TOP_LEFT) {
+                    adjustCorner(cropRect.left + dx, cropRect.top + dy, true, true);
+                } else if (activeCorner == CORNER_TOP_RIGHT) {
+                    adjustCorner(cropRect.right + dx, cropRect.top + dy, false, true);
+                } else if (activeCorner == CORNER_BOTTOM_LEFT) {
+                    adjustCorner(cropRect.left + dx, cropRect.bottom + dy, true, false);
+                } else if (activeCorner == CORNER_BOTTOM_RIGHT) {
+                    adjustCorner(cropRect.right + dx, cropRect.bottom + dy, false, false);
+                }
+                
+                lastX = x;
+                lastY = y;
+                invalidate();
+                return true;
+                
+            case MotionEvent.ACTION_UP:
+                activeCorner = -1;
+                return true;
+        }
+        return super.onTouchEvent(event);
+    }
+    
+    private void adjustCorner(float nx, float ny, boolean left, boolean top) {
+        float newWidth;
+        float newLeft = cropRect.left;
+        float newTop = cropRect.top;
+        float newRight = cropRect.right;
+        float newBottom = cropRect.bottom;
+        
+        if (left) {
+            newWidth = cropRect.width() - (nx - cropRect.left);
+            newLeft = Math.max(canvasBounds.left, Math.min(nx, cropRect.right - minSize));
+        } else {
+            newWidth = nx - cropRect.left;
+            newRight = Math.min(canvasBounds.right, Math.max(nx, cropRect.left + minSize));
+            newLeft = cropRect.left;
+        }
+        
+        float newHeight = newWidth / coverRatio;
+        
+        if (top) {
+            newTop = Math.max(canvasBounds.top, Math.min(cropRect.bottom - minSize, cropRect.bottom - newHeight));
+            newBottom = newTop + newHeight;
+        } else {
+            newBottom = Math.min(canvasBounds.bottom, Math.max(cropRect.top + minSize, cropRect.top + newHeight));
+            newTop = newBottom - newHeight;
+        }
+        
+        if (left) {
+            cropRect.left = newLeft;
+            cropRect.right = newLeft + newWidth;
+        } else {
+            cropRect.right = newRight;
+            cropRect.left = newRight - newWidth;
+        }
+        
+        if (top) {
+            cropRect.top = newTop;
+            cropRect.bottom = newTop + newHeight;
+        } else {
+            cropRect.bottom = newBottom;
+            cropRect.top = newBottom - newHeight;
+        }
+    }
+    
+    private int getActiveCorner(float x, float y) {
+        float dx = Math.abs(x - cropRect.left);
+        float dy = Math.abs(y - cropRect.top);
+        float dx2 = Math.abs(x - cropRect.right);
+        float dy2 = Math.abs(y - cropRect.bottom);
+        
+        if (dx <= touchArea && dy <= touchArea) {
+            return CORNER_TOP_LEFT;
+        }
+        if (dx2 <= touchArea && dy <= touchArea) {
+            return CORNER_TOP_RIGHT;
+        }
+        if (dx <= touchArea && dy2 <= touchArea) {
+            return CORNER_BOTTOM_LEFT;
+        }
+        if (dx2 <= touchArea && dy2 <= touchArea) {
+            return CORNER_BOTTOM_RIGHT;
+        }
+        if (x > cropRect.left && x < cropRect.right && y > cropRect.top && y < cropRect.bottom) {
+            return CORNER_CENTER;
+        }
+        return -1;
+    }
+    
+    private float getSpan(MotionEvent event) {
+        float x0 = event.getX(0);
+        float y0 = event.getY(0);
+        float x1 = event.getX(1);
+        float y1 = event.getY(1);
+        return (float) Math.sqrt((x1 - x0) * (x1 - x0) + (y1 - y0) * (y1 - y0));
+    }
+    
+    public int getColorAt(float x, float y) {
+        if (canvasBitmap != null && !canvasBitmap.isRecycled()) {
+            int bitmapX = (int) x;
+            int bitmapY = (int) y;
+            if (bitmapX >= 0 && bitmapX < canvasBitmap.getWidth() && 
+                bitmapY >= 0 && bitmapY < canvasBitmap.getHeight()) {
+                return canvasBitmap.getPixel(bitmapX, bitmapY);
+            }
+        }
+        return Color.TRANSPARENT;
+    }
+}

gallery/src/main/java/cc/winboll/studio/gallery/CropOverlayView.java

@@ -0,0 +1,224 @@
+package cc.winboll.studio.gallery;
+
+import android.content.Context;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Paint;
+import android.graphics.RectF;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import android.view.View;
+
+public class CropOverlayView extends View {
+    public interface OnCanvasSizeChangedListener {
+        void onCanvasSizeChanged(RectF canvasBounds);
+    }
+    
+    private OnCanvasSizeChangedListener canvasSizeChangedListener;
+    
+    private Paint borderPaint;
+    private Paint cornerPaint;
+    private RectF cropRect;
+    private int touchArea = 50;
+    
+    private float lastX, lastY;
+    private int activeCorner = -1;
+    private static final int CORNER_TOP_LEFT = 0;
+    private static final int CORNER_TOP_RIGHT = 1;
+    private static final int CORNER_BOTTOM_LEFT = 2;
+    private static final int CORNER_BOTTOM_RIGHT = 3;
+    private static final int CORNER_CENTER = 4;
+    
+    private float targetRatio = 2.0f;
+    private RectF canvasBounds = new RectF();
+    private float minSize = 50;
+    
+    public CropOverlayView(Context context) {
+        super(context);
+        initPaints();
+    }
+    
+    public CropOverlayView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        initPaints();
+    }
+    
+    public CropOverlayView(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+        initPaints();
+    }
+    
+    private void initPaints() {
+        borderPaint = new Paint();
+        borderPaint.setColor(Color.parseColor("#CCAA00"));
+        borderPaint.setStyle(Paint.Style.STROKE);
+        borderPaint.setStrokeWidth(3);
+        
+        cornerPaint = new Paint();
+        cornerPaint.setColor(Color.WHITE);
+        cornerPaint.setStyle(Paint.Style.FILL);
+    }
+    
+    public void setTargetRatio(float ratio) {
+        this.targetRatio = ratio;
+    }
+    
+    public float getTargetRatio() {
+        return targetRatio;
+    }
+    
+    public void setOnCanvasSizeChangedListener(OnCanvasSizeChangedListener listener) {
+        this.canvasSizeChangedListener = listener;
+    }
+    
+    public void initCanvas(int canvasW, int canvasH) {
+        canvasBounds.set(0, 0, canvasW, canvasH);
+        
+        cropRect = new RectF(0, 0, canvasW, canvasH);
+        
+        if (canvasSizeChangedListener != null) {
+            canvasSizeChangedListener.onCanvasSizeChanged(new RectF(canvasBounds));
+        }
+        invalidate();
+    }
+    
+    public RectF getCropRect() {
+        return new RectF(cropRect);
+    }
+    
+    public RectF getCanvasBounds() {
+        return new RectF(canvasBounds);
+    }
+    
+    @Override
+    protected void onDraw(Canvas canvas) {
+        super.onDraw(canvas);
+        
+        canvas.drawColor(Color.TRANSPARENT);
+        
+        if (cropRect != null) {
+            canvas.drawRect(cropRect, borderPaint);
+            
+            canvas.drawCircle(cropRect.left, cropRect.top, 12, cornerPaint);
+            canvas.drawCircle(cropRect.right, cropRect.top, 12, cornerPaint);
+            canvas.drawCircle(cropRect.left, cropRect.bottom, 12, cornerPaint);
+            canvas.drawCircle(cropRect.right, cropRect.bottom, 12, cornerPaint);
+        }
+    }
+    
+    @Override
+    public boolean onTouchEvent(MotionEvent event) {
+        if (cropRect == null || canvasBounds.isEmpty()) return false;
+        
+        float x = event.getX();
+        float y = event.getY();
+        
+        switch (event.getAction()) {
+            case MotionEvent.ACTION_DOWN:
+                lastX = x;
+                lastY = y;
+                activeCorner = getActiveCorner(x, y);
+                return true;
+                
+            case MotionEvent.ACTION_MOVE:
+                float dx = x - lastX;
+                float dy = y - lastY;
+                
+                if (activeCorner == CORNER_CENTER) {
+                    float newLeft = cropRect.left + dx;
+                    float newTop = cropRect.top + dy;
+                    float newRight = cropRect.right + dx;
+                    float newBottom = cropRect.bottom + dy;
+                    
+                    if (newLeft >= canvasBounds.left && newRight <= canvasBounds.right) {
+                        cropRect.left = newLeft;
+                        cropRect.right = newRight;
+                    }
+                    if (newTop >= canvasBounds.top && newBottom <= canvasBounds.bottom) {
+                        cropRect.top = newTop;
+                        cropRect.bottom = newBottom;
+                    }
+                } else if (activeCorner == CORNER_TOP_LEFT) {
+                    adjustCorner(cropRect.left + dx, cropRect.top + dy, true, true);
+                } else if (activeCorner == CORNER_TOP_RIGHT) {
+                    adjustCorner(cropRect.right + dx, cropRect.top + dy, false, true);
+                } else if (activeCorner == CORNER_BOTTOM_LEFT) {
+                    adjustCorner(cropRect.left + dx, cropRect.bottom + dy, true, false);
+                } else if (activeCorner == CORNER_BOTTOM_RIGHT) {
+                    adjustCorner(cropRect.right + dx, cropRect.bottom + dy, false, false);
+                }
+                
+                lastX = x;
+                lastY = y;
+                invalidate();
+                return true;
+                
+            case MotionEvent.ACTION_UP:
+                activeCorner = -1;
+                return true;
+        }
+        return super.onTouchEvent(event);
+    }
+    
+    private void adjustCorner(float nx, float ny, boolean left, boolean top) {
+        float newWidth;
+        float newLeft = cropRect.left;
+        float newTop = cropRect.top;
+        float newRight = cropRect.right;
+        float newBottom = cropRect.bottom;
+        
+        if (left) {
+            newWidth = cropRect.width() - (nx - cropRect.left);
+            newLeft = Math.max(canvasBounds.left, Math.min(nx, cropRect.right - minSize));
+        } else {
+            newWidth = nx - cropRect.left;
+            newRight = Math.min(canvasBounds.right, Math.max(nx, cropRect.left + minSize));
+            newLeft = cropRect.left;
+        }
+        
+        float newHeight = newWidth / targetRatio;
+        
+        if (top) {
+            newTop = Math.max(canvasBounds.top, Math.min(cropRect.bottom - minSize, cropRect.bottom - newHeight));
+            newBottom = newTop + newHeight;
+        } else {
+            newBottom = Math.min(canvasBounds.bottom, Math.max(cropRect.top + minSize, cropRect.top + newHeight));
+            newTop = newBottom - newHeight;
+        }
+        
+        if (left) {
+            cropRect.left = newLeft;
+            cropRect.right = newLeft + newWidth;
+        } else {
+            cropRect.right = newRight;
+            cropRect.left = newRight - newWidth;
+        }
+        
+        if (top) {
+            cropRect.top = newTop;
+            cropRect.bottom = newTop + newHeight;
+        } else {
+            cropRect.bottom = newBottom;
+            cropRect.top = newBottom - newHeight;
+        }
+    }
+    
+    private int getActiveCorner(float x, float y) {
+        if (Math.abs(x - cropRect.left) <= touchArea && Math.abs(y - cropRect.top) <= touchArea) {
+            return CORNER_TOP_LEFT;
+        }
+        if (Math.abs(x - cropRect.right) <= touchArea && Math.abs(y - cropRect.top) <= touchArea) {
+            return CORNER_TOP_RIGHT;
+        }
+        if (Math.abs(x - cropRect.left) <= touchArea && Math.abs(y - cropRect.bottom) <= touchArea) {
+            return CORNER_BOTTOM_LEFT;
+        }
+        if (Math.abs(x - cropRect.right) <= touchArea && Math.abs(y - cropRect.bottom) <= touchArea) {
+            return CORNER_BOTTOM_RIGHT;
+        }
+        if (cropRect.contains(x, y)) {
+            return CORNER_CENTER;
+        }
+        return -1;
+    }
+}

gallery/src/main/res/drawable/ic_close.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="#FFFFFF"
+        android:pathData="M19,6.41L17.59,5 12,10.59 6.41,5 5,6.41 10.59,12 5,17.59 6.41,19 12,13.41 17.59,19 19,17.59 13.41,12z"/>
+</vector>

gallery/src/main/res/drawable/ic_color_pick.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="#FFFFFF"
+        android:pathData="M20.71,5.63l-2.34,-2.34c-0.39,-0.39 -1.02,-0.39 -1.41,0l-3.12,3.12 -1.93,-1.91 -1.41,1.41 1.42,1.42L3,16.25V21h4.75l8.92,-8.92 1.42,1.42 1.41,-1.41 -1.92,-1.92 3.12,-3.12c0.4,-0.4 0.4,-1.03 0.01,-1.42zM6.92,19H5v-1.92l8.06,-8.06 1.92,1.92L6.92,19z"/>
+</vector>

gallery/src/main/res/layout/activity_crop.xml

@@ -0,0 +1,56 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:background="@color/black">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="56dp"
+        android:orientation="horizontal"
+        android:gravity="center_vertical"
+        android:background="@color/colorPrimary"
+        android:paddingHorizontal="16dp">
+
+        <ImageView
+            android:id="@+id/btn_close"
+            android:layout_width="48dp"
+            android:layout_height="48dp"
+            android:padding="12dp"
+            android:src="@drawable/ic_close"
+            android:background="?attr/selectableItemBackgroundBorderless"/>
+
+        <ImageView
+            android:id="@+id/btn_color_pick"
+            android:layout_width="48dp"
+            android:layout_height="48dp"
+            android:padding="12dp"
+            android:src="@drawable/ic_color_pick"
+            android:background="?attr/selectableItemBackgroundBorderless"/>
+
+        <View
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            android:layout_weight="1"/>
+
+        <TextView
+            android:id="@+id/btn_done"
+            android:layout_width="wrap_content"
+            android:layout_height="48dp"
+            android:text="完成"
+            android:textColor="@android:color/white"
+            android:textSize="16sp"
+            android:gravity="center"
+            android:paddingHorizontal="16dp"
+            android:background="?attr/selectableItemBackgroundBorderless"/>
+
+    </LinearLayout>
+
+    <cc.winboll.studio.gallery.CropCanvasView
+        android:id="@+id/crop_canvas_view"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:layout_gravity="center"/>
+
+</FrameLayout>

gallery/src/main/res/menu/menu_crop.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+    <item
+        android:id="@+id/action_done"
+        android:title="完成"
+        app:showAsAction="always"/>
+</menu>