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

@@ -7,6 +7,7 @@ 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;
@@ -55,6 +56,16 @@ public class CropActivity extends AppCompatActivity {
             }
         });
         
+        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) {
@@ -107,36 +118,26 @@ public class CropActivity extends AppCompatActivity {
     }
     
     private void saveCroppedCover() {
-        if (originalBitmap == null) {
+        Bitmap canvasBitmap = cropCanvasView.getCanvasBitmap();
+        if (canvasBitmap == null) {
             Toast.makeText(this, "Failed to get image", Toast.LENGTH_SHORT).show();
             return;
         }
         
         try {
             RectF cropRect = cropCanvasView.getCropRect();
-            RectF canvasBounds = cropCanvasView.getCanvasBounds();
-            RectF imageBounds = cropCanvasView.getImageBounds();
             
-            int imgW = originalBitmap.getWidth();
+            int cropX = (int) cropRect.left;
-            int imgH = originalBitmap.getHeight();
+            int cropY = (int) cropRect.top;
+            int cropW = (int) cropRect.width();
+            int cropH = (int) cropRect.height();
             
-            float scaleX = (float) imgW / canvasBounds.width();
+            cropX = Math.max(0, Math.min(cropX, canvasBitmap.getWidth() - 1));
-            float scaleY = (float) imgH / canvasBounds.height();
+            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));
             
-            float canvasLeft = cropRect.left - canvasBounds.left;
+            Bitmap cropped = Bitmap.createBitmap(canvasBitmap, cropX, cropY, cropW, cropH);
-            float canvasTop = cropRect.top - canvasBounds.top;
-            
-            int cropX = (int) ((canvasLeft - imageBounds.left) * scaleX);
-            int cropY = (int) ((canvasTop - imageBounds.top) * scaleY);
-            int cropW = (int) (cropRect.width() * scaleX);
-            int cropH = (int) (cropRect.height() * scaleY);
-            
-            cropX = Math.max(0, Math.min(cropX, imgW - 1));
-            cropY = Math.max(0, Math.min(cropY, imgH - 1));
-            cropW = Math.max(1, Math.min(cropW, imgW - cropX));
-            cropH = Math.max(1, Math.min(cropH, imgH - cropY));
-            
-            Bitmap cropped = Bitmap.createBitmap(originalBitmap, cropX, cropY, cropW, cropH);
             
             File cacheDir = getCacheDir();
             File coverFile = new File(cacheDir, "cover_" + System.currentTimeMillis() + ".png");

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

@@ -38,7 +38,11 @@ public class CropCanvasView extends View {
     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);
@@ -98,10 +102,51 @@ public class CropCanvasView extends View {
         
         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);
@@ -141,14 +186,6 @@ public class CropCanvasView extends View {
         return canvasHeight;
     }
     
-    public int getExtendWidth() {
-        return extendWidth;
-    }
-    
-    public int getExtendHeight() {
-        return extendHeight;
-    }
-    
     public RectF getCanvasBounds() {
         return new RectF(canvasBounds);
     }
@@ -157,10 +194,6 @@ public class CropCanvasView extends View {
         return new RectF(imageBounds);
     }
     
-    public float getCoverRatio() {
-        return coverRatio;
-    }
-    
     @Override
     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
         int w = canvasWidth > 0 ? canvasWidth : 0;
@@ -172,10 +205,8 @@ public class CropCanvasView extends View {
     protected void onDraw(Canvas canvas) {
         super.onDraw(canvas);
         
-        canvas.drawColor(Color.GREEN);
+        if (canvasBitmap != null && !canvasBitmap.isRecycled()) {
-        
+            canvas.drawBitmap(canvasBitmap, 0, 0, null);
-        if (originalBitmap != null && !originalBitmap.isRecycled()) {
-            canvas.drawBitmap(originalBitmap, imageBounds.left, imageBounds.top, imagePaint);
         }
         
         if (cropRect != null) {
@@ -222,6 +253,17 @@ public class CropCanvasView extends View {
         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;
@@ -313,19 +355,24 @@ public class CropCanvasView extends View {
     }
     
     private int getActiveCorner(float x, float y) {
-        if (Math.abs(x - cropRect.left) <= touchArea && Math.abs(y - cropRect.top) <= touchArea) {
+        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 (Math.abs(x - cropRect.right) <= touchArea && Math.abs(y - cropRect.top) <= touchArea) {
+        if (dx2 <= touchArea && dy <= touchArea) {
             return CORNER_TOP_RIGHT;
         }
-        if (Math.abs(x - cropRect.left) <= touchArea && Math.abs(y - cropRect.bottom) <= touchArea) {
+        if (dx <= touchArea && dy2 <= touchArea) {
             return CORNER_BOTTOM_LEFT;
         }
-        if (Math.abs(x - cropRect.right) <= touchArea && Math.abs(y - cropRect.bottom) <= touchArea) {
+        if (dx2 <= touchArea && dy2 <= touchArea) {
             return CORNER_BOTTOM_RIGHT;
         }
-        if (cropRect.contains(x, y)) {
+        if (x > cropRect.left && x < cropRect.right && y > cropRect.top && y < cropRect.bottom) {
             return CORNER_CENTER;
         }
         return -1;
@@ -338,4 +385,16 @@ public class CropCanvasView extends View {
         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/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

@@ -21,6 +21,14 @@
             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"