绘制后位图不在画布上

Question

我在画布上绘制了canvas.drawBitmap(bmp, 0, 0, null);的位图，位图将不显示。有任何想法吗？

谢谢！

  Bitmap bmp = BitmapFactory.decodeFile(myfile.getPath()); 
      //Bitmap bmp = BitmapFactory.decodeStream(bis); 

      Log.i(TAG, "builded Bitmap");    
      Log.i(TAG, "scaling bitmap..."); 


      //int scale; 
      //Matrix matrix = new Matrix(); 
      //matrix.setScale(0.1F, 0.1F); 
      //if (bmp.getWidth() < bmp.getHeight()){ 
      // scale = canvas.getWidth()/bmp.getWidth(); 
      //}else{ 
      // scale = canvas.getHeight()/bmp.getHeight(); 
      //} 
      //matrix.postScale(scale, scale, bmp.getWidth(), bmp.getHeight()); 
      //matrix.postScale(0.5F, canvas.getWidth()/bmp.getWidth()); 

      //Bitmap bmp2 = Bitmap.createScaledBitmap(bmp, canvas.getWidth(), canvas.getHeight(), true); 

      //Paint p = new Paint(); 
      //p.setFilterBitmap(true); 


      //try{ 
      bmp = Bitmap.createScaledBitmap(bmp, canvas.getWidth(), canvas.getHeight(), true); 
      Log.i(TAG, "scaled"); 
      Log.i(TAG, "showing bitmap..."); 
      canvas.drawBitmap(bmp, 0, 0, null); 
      Log.i(TAG, "showed bitmap"); 

Answer 1

你能画一条线吗？ 可以调用invalidate（）或postInvalidate（）。

读绘画这里： http://developer.android.com/reference/android/view/View.html

并且拷贝一些例子，如： http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/graphics/TouchPaint.html

Answer 2

只是一个猜测：

而不是“BMP位图= BitmapFactory.decodeFile（myfile.getPath（）） ; “尝试”位图bmp = BitmapFactory.decodeStream（..）;“