Android：如何撤消已绘制到 canvas 的位图？

Question

我正在将可绘制对象放在 canvas 之类的标记上，将最终位图设置为 ImageView。如何添加一次可以撤消一个可绘制对象的撤消功能？请帮忙。

这是我的代码：

Bitmap bitmap = ((BitmapDrawable) imageView.getDrawable()).getBitmap();

//Create a new image bitmap and attach a brand new canvas to it
Bitmap tempBitmap = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Bitmap.Config.RGB_565);

 Canvas tempCanvas = new Canvas(tempBitmap);

 //Draw the image bitmap into the canvas
 tempCanvas.drawBitmap(bitmap, 0, 0, null);

 Bitmap marker = BitmapFactory.decodeResource(getResources(), R.drawable.check);

 //Draw into the canvas
 tempCanvas.drawBitmap(marker, x, y, null);

 //Attach the canvas to the ImageView
 imageView.setImageDrawable(new BitmapDrawable(getResources(), tempBitmap));

Answer 1

我想出了一个窍门。我使用 ArrayList 在每次放置标记后存储带注释的位图。我只是从列表中弹出最后一项并在撤消时显示新的位图。如果有人有兴趣，这里是代码：

bitmapLayers.add(annotatedBitmap);

对于撤消：

if (!bitmapLayers.isEmpty())
{
      bitmapLayers.remove(bitmapLayers.size() - 1);
      Bitmap last = bitmapLayers.get(bitmapLayers.size() - 1);
      imageView.setImageBitmap(last);

      //If no undos left, hide button
      if (bitmapLayers.size() == 1)
      {
          mUndo.setVisible(false);
      }
 }

如果有人能提供优化的方案就好了

Android：如何撤消已绘制到 canvas 的位图？

Android: How do I undo a bitmap which has been drawn to a canvas?

android

canvas

bitmap

markers