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Learning MIT App Inventor: A Hands-On Guide to Building Your Own Android Apps by Mark Sherman, Derek Walter

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Canvas

To use the aforementioned sprites, you need a canvas. As you saw in Flick, this is where you place a sprite or ball.

Basic possible changes include color, width, height, and background image. Additionally, you can specify any location on a canvas as a pair of (x, y) values, where x is the number of pixels away from the left edge of the canvas and y is the number away from the top edge (see Figure 7.3). The maximum values of x and y depend on the size of the canvas, which can vary app to app and from phone to phone. You can always find the maximum values by reading the width and height of the canvas, which you do by getting the Canvas.Width and Canvas.Height properties, as in Figure 7.4.

Figure 7.3 The canvas coordinate system. Numbers ...

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