Add Image Editor support for blur mask layer.

app/src/main/java/org/thoughtcrime/securesms/imageeditor/RendererContext.java

@@ -3,11 +3,17 @@ package org.thoughtcrime.securesms.imageeditor;
 import android.content.Context;
 import android.graphics.Canvas;
 import android.graphics.Matrix;
+import android.graphics.Paint;
 import android.graphics.Point;
 import android.graphics.RectF;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
+import org.thoughtcrime.securesms.imageeditor.model.EditorElement;
+
+import java.util.Collections;
+import java.util.List;
+
 /**
  * Contains all of the information required for a {@link Renderer} to do its job.
  * <p>
@@ -38,6 +44,9 @@ public final class RendererContext {
 
   private boolean isEditing = true;
 
+  private List<EditorElement> children = Collections.emptyList();
+  private Paint               maskPaint;
+
   public RendererContext(@NonNull Context context, @NonNull Canvas canvas, @NonNull Ready rendererReady, @NonNull Invalidate invalidate) {
     this.context       = context;
     this.canvas        = canvas;
@@ -100,6 +109,22 @@ public final class RendererContext {
     canvasMatrix.getCurrent(into);
   }
 
+  public void setChildren(@NonNull List<EditorElement> children) {
+    this.children = children;
+  }
+
+  public @NonNull List<EditorElement> getChildren() {
+    return children;
+  }
+
+  public void setMaskPaint(@Nullable Paint maskPaint) {
+    this.maskPaint = maskPaint;
+  }
+
+  public @Nullable Paint getMaskPaint() {
+    return maskPaint;
+  }
+
   public interface Ready {
 
     Ready NULL = (renderer, cropMatrix, size) -> {

app/src/main/java/org/thoughtcrime/securesms/imageeditor/model/EditorElement.java

@@ -97,7 +97,7 @@ public final class EditorElement implements Parcelable {
    *
    * @param rendererContext Canvas to draw on to.
    */
-  void draw(@NonNull RendererContext rendererContext) {
+  public void draw(@NonNull RendererContext rendererContext) {
     if (!flags.isVisible() && !flags.isChildrenVisible()) return;
 
     rendererContext.save();
@@ -113,6 +113,7 @@ public final class EditorElement implements Parcelable {
       float alpha = alphaAnimation.getValue();
       if (alpha > 0) {
         rendererContext.setFade(alpha);
+        rendererContext.setChildren(children);
         drawSelf(rendererContext);
         rendererContext.setFade(1f);
       }
@@ -133,9 +134,11 @@ public final class EditorElement implements Parcelable {
 
   private static void drawChildren(@NonNull List<EditorElement> children, @NonNull RendererContext rendererContext) {
     for (EditorElement element : children) {
+      if (element.zOrder >= 0) {
         element.draw(rendererContext);
       }
     }
+  }
 
   public void addElement(@NonNull EditorElement element) {
     children.add(element);
@@ -252,6 +255,10 @@ public final class EditorElement implements Parcelable {
     animationMatrix = AnimationMatrix.singlePulse(scale, invalidate);
   }
 
+  public int getZOrder() {
+    return zOrder;
+  }
+
   public interface PerElementFunction {
     void apply(EditorElement element);
   }

app/src/main/java/org/thoughtcrime/securesms/imageeditor/model/EditorModel.java

@@ -35,6 +35,7 @@ import java.util.UUID;
  */
 public final class EditorModel implements Parcelable, RendererContext.Ready {
 
+  public static final int Z_MASK     = -1;
   public static final int Z_DRAWING  = 0;
   public static final int Z_STICKERS = 0;
   public static final int Z_TEXT     = 1;

app/src/main/java/org/thoughtcrime/securesms/imageeditor/renderers/BezierDrawingRenderer.java

@@ -98,6 +98,8 @@ public final class BezierDrawingRenderer extends InvalidateableRenderer implemen
     int alpha = paint.getAlpha();
     paint.setAlpha(rendererContext.getAlpha(alpha));
 
+    paint.setXfermode(rendererContext.getMaskPaint() != null ? rendererContext.getMaskPaint().getXfermode() : null);
+
     bezierLine.draw(canvas, paint);
 
     paint.setAlpha(alpha);

app/src/main/java/org/thoughtcrime/securesms/scribbles/UriGlideRenderer.java

@@ -2,13 +2,20 @@ package org.thoughtcrime.securesms.scribbles;
 
 import android.content.Context;
 import android.graphics.Bitmap;
+import android.graphics.BlurMaskFilter;
 import android.graphics.Matrix;
 import android.graphics.Paint;
 import android.graphics.Point;
+import android.graphics.PorterDuff;
+import android.graphics.PorterDuffXfermode;
 import android.graphics.RectF;
 import android.graphics.drawable.Drawable;
 import android.net.Uri;
 import android.os.Parcel;
+import android.renderscript.Allocation;
+import android.renderscript.Element;
+import android.renderscript.RenderScript;
+import android.renderscript.ScriptIntrinsicBlur;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
@@ -20,6 +27,8 @@ import com.bumptech.glide.request.transition.Transition;
 import org.thoughtcrime.securesms.imageeditor.Bounds;
 import org.thoughtcrime.securesms.imageeditor.Renderer;
 import org.thoughtcrime.securesms.imageeditor.RendererContext;
+import org.thoughtcrime.securesms.imageeditor.model.EditorElement;
+import org.thoughtcrime.securesms.imageeditor.model.EditorModel;
 import org.thoughtcrime.securesms.mms.DecryptableStreamUriLoader;
 import org.thoughtcrime.securesms.mms.GlideApp;
 import org.thoughtcrime.securesms.mms.GlideRequest;
@@ -43,8 +52,10 @@ final class UriGlideRenderer implements Renderer {
   private final int     maxWidth;
   private final int     maxHeight;
 
-  @Nullable
+  @Nullable private Bitmap         bitmap;
-  private Bitmap bitmap;
+  @Nullable private Bitmap         blurredBitmap;
+  @Nullable private Paint          blurPaint;
+  @Nullable private BlurMaskFilter blurMaskFilter;
 
   UriGlideRenderer(@NonNull Uri imageUri, boolean decryptable, int maxWidth, int maxHeight) {
     this.imageUri    = imageUri;
@@ -94,17 +105,52 @@ final class UriGlideRenderer implements Renderer {
       int alpha = paint.getAlpha();
       paint.setAlpha(rendererContext.getAlpha(alpha));
 
-      rendererContext.canvas.drawBitmap(bitmap, 0, 0, paint);
+      rendererContext.canvas.drawBitmap(bitmap, 0, 0, rendererContext.getMaskPaint() != null ? rendererContext.getMaskPaint() : paint);
 
       paint.setAlpha(alpha);
 
       rendererContext.restore();
+
+      renderBlurOverlay(rendererContext);
     } else if (rendererContext.isBlockingLoad()) {
       // If failed to load, we draw a black out, in case image was sticker positioned to cover private info.
       rendererContext.canvas.drawRect(Bounds.FULL_BOUNDS, paint);
     }
   }
 
+  private void renderBlurOverlay(RendererContext rendererContext) {
+      boolean renderMask = false;
+
+      for (EditorElement child : rendererContext.getChildren()) {
+        if (child.getZOrder() == EditorModel.Z_MASK) {
+          renderMask = true;
+          if (blurMaskFilter == null) {
+            blurMaskFilter = new BlurMaskFilter(4, BlurMaskFilter.Blur.NORMAL); // This blurs edges of the mask shapes
+          }
+          if (blurPaint == null) {
+            blurPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
+            blurPaint.setMaskFilter(blurMaskFilter);
+          }
+          blurPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));
+          rendererContext.setMaskPaint(blurPaint);
+          child.draw(rendererContext);
+        }
+      }
+
+    if (renderMask) {
+      rendererContext.save();
+      rendererContext.canvasMatrix.concat(imageProjectionMatrix);
+
+      blurPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_ATOP));
+      blurPaint.setMaskFilter(null);
+      if (blurredBitmap == null) blurredBitmap = blur(bitmap, rendererContext.context);
+      rendererContext.canvas.drawBitmap(blurredBitmap, 0, 0, blurPaint);
+      blurPaint.setXfermode(null);
+
+      rendererContext.restore();
+    }
+  }
+
   private GlideRequest<Bitmap> getBitmapGlideRequest(@NonNull Context context, boolean preview) {
     int width  = this.maxWidth;
     int height = this.maxHeight;
@@ -177,6 +223,21 @@ final class UriGlideRenderer implements Renderer {
     return matrix;
   }
 
+  private static @NonNull Bitmap blur(@NonNull Bitmap bitmap, @NonNull Context context) {
+    RenderScript        rs     = RenderScript.create(context);
+    Allocation          input  = Allocation.createFromBitmap(rs, bitmap);
+    Allocation          output = Allocation.createTyped     (rs, input.getType());
+    ScriptIntrinsicBlur script = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
+
+    script.setRadius(25f);
+    script.setInput(input);
+    script.forEach(output);
+
+    Bitmap blurred = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), bitmap.getConfig());
+    output.copyTo(blurred);
+    return blurred;
+  }
+
   public static final Creator<UriGlideRenderer> CREATOR = new Creator<UriGlideRenderer>() {
     @Override
     public UriGlideRenderer createFromParcel(Parcel in) {