Is Android canvas.drawBitmap documentation wrong?

0
votes

Is the Android documentation for canvas.drawBitmap wrong? It says:

public void drawBitmap (Bitmap bitmap, float left, float top, Paint paint)

Draw the specified bitmap, with its top/left corner at (x,y), using the specified paint, transformed by the current matrix.

Well, x and y don’t seem to be floats, they’re ints; is that correct? Say I want to overlay the bitmap (which is the size of the available screen, and is bound to a canvas of the same) over the whole available screen. It seems sensible I would: canvas.drawBitmap(myBitmap, 0, 0, mPaint); doesn’t it? But that doesn’t work. What does seem to work is: canvas.drawBitmap(myBitmap, 2000000, 1000000, mPaint). Now that statement seems to me to tell the bitmap that it should draw itself a huge distance Outside the screen! What am I missing here?

1
androidandroid-maps
Android documentation is correct, (0,0) is the top left corner of the screen. Can you edit your question with your codes. – NaviRamyle
"transformed by the current matrix.", have you check to make sure do not have some translations in your canvas matrix? – iagreen

1 Answers

1
votes

In this method x and y are floats, not ints. But like mentioned in the documentation, the x and y coordinates of the bitmaps will be affected by the matrix currently set on the Canvas. In the case of a ScrollView for instance, the matrix could very well contain a very large translation.

What this means is that the coordinates 0, 0 will draw the bitmap at the current origin of the Canvas. That origin is defined by the matrix you can query with getMatrix().