向像Snapchat这样的图片中添加带有灰色背景的文本？ Android / Java

Question

          Bitmap newBm = ...
          Canvas canvas = new Canvas(newBm);
          Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
          paint.setColor(Color.WHITE);
          paint.setTextSize((int) (44 * scale));
          Rect bounds = new Rect();
          paint.getTextBounds(gText, 0, gText.length(), bounds);
          canvas.drawText(gText, x, y, paint);

I drew text on the Bitmap like so. How could I get a grey background that is the same height as the text but covers the whole screen??

Answer 1

The best way to see and learn how these sort of things are done with well written code is to look at the android source code itself. For example here is the onDraw method for a TextView it includes additional stuff you won't probably need like compoundPadding, but you can follow it through and get the basic concept of how it's done.

Answer 2

You could use a Rect . Before drawing the text draw the Rect to the screen:

int screenWidth = getApplicationContext().getResources().getDisplayMetrics().widthPixels; Rect greyBack = new Rect(0,top,screenWidth,bottom); Paint paint = new Paint(); paint.setARGB(128, 100, 100, 100); //added alpha because Snapchat has translucent //grey background canvas.drawRect(greyBack, paint);

top and bottom need to be coordinates above and below the text. You could use y 's value and take away a bit for top and add a bit for bottom . How much you add/subtract is up to you and changes the height of the greyBack background.