Signal-Android/app/src/main/java/org/thoughtcrime/securesms/components/MaskView.java

96 lines
2.6 KiB
Java

package org.thoughtcrime.securesms.components;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewTreeObserver;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
public class MaskView extends View {
private View target;
private ViewGroup activityContentView;
private Paint maskPaint;
private Rect drawingRect = new Rect();
private float targetParentTranslationY;
private final ViewTreeObserver.OnDrawListener onDrawListener = this::invalidate;
public MaskView(@NonNull Context context) {
super(context);
}
public MaskView(@NonNull Context context, @Nullable AttributeSet attributeSet) {
super(context, attributeSet);
}
@Override
protected void onFinishInflate() {
super.onFinishInflate();
maskPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
setLayerType(LAYER_TYPE_HARDWARE, maskPaint);
maskPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));
}
@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
activityContentView = getRootView().findViewById(android.R.id.content);
}
public void setTarget(@Nullable View target) {
if (this.target != null) {
this.target.getViewTreeObserver().removeOnDrawListener(onDrawListener);
}
this.target = target;
if (this.target != null) {
this.target.getViewTreeObserver().addOnDrawListener(onDrawListener);
}
invalidate();
}
public void setTargetParentTranslationY(float targetParentTranslationY) {
this.targetParentTranslationY = targetParentTranslationY;
}
@Override
protected void onDraw(@NonNull Canvas canvas) {
super.onDraw(canvas);
if (target == null || !target.isAttachedToWindow()) {
return;
}
target.getDrawingRect(drawingRect);
activityContentView.offsetDescendantRectToMyCoords(target, drawingRect);
drawingRect.bottom = Math.min(drawingRect.bottom, getBottom() - getPaddingBottom());
drawingRect.top += targetParentTranslationY;
drawingRect.bottom += targetParentTranslationY;
Bitmap mask = Bitmap.createBitmap(target.getWidth(), drawingRect.height(), Bitmap.Config.ARGB_8888);
Canvas maskCanvas = new Canvas(mask);
target.draw(maskCanvas);
canvas.drawBitmap(mask, 0, drawingRect.top, maskPaint);
mask.recycle();
}
}