Apple Newton Utilities Guide de l'utilisateur télécharger pdf (Page 543)

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CHAPTER 13

Drawing and Graphics

Using the Drawing Interface 13-17

Using Bitmaps 13

You can dynamically create and destroy bitmaps, draw into them, and perform

operations on them such as rotating, ﬂipping, and sizing. This ﬂexible treatment of

bitmaps allows you to use them as offscreen buffers and for storage of documents

such as fax pages.

You can create and use bitmap images with the drawing bitmap functions. To create

a bitmap you ﬁrst allocate a bitmap that will contain the drawing with the

MakeBitmap function. Then create a shape with the MakeShape function.

DrawIntoBitmap takes the drawing and draws it into the bitmap. The final step

is to draw the bitmap on the Newton screen with the

DrawShape function.

The following example shows how to draw a bitmap. It creates a bitmap by drawing

a shape and draws it onto the screen. This example then rotates the shape, scales it,

and redraws it on the Newton:

bitmapWidth := 90;

bitmapHeight := 120;

vfBlack := 5;

// allocate a new bitmap

bitmap := MakeBitmap(bitmapWidth, bitmapHeight, nil);

// make a shape and draw it into the bitmap

shapes := MakeOval(0, 0, 50, 75);

DrawIntoBitmap(shapes, {fillPattern: vfBlack}, bitmap);

// draw the bitmap

GetRoot():DrawShape(bitmap, {transform: [100, 100]});

// Rotation is a destructive operation: it replaces the

// old bitmap with the new rotated bitmap.

MungeBitmap(bitmap, 'rotateRight, nil);

// translate and scale the bitmap

fromRect := SetBounds(0, 0, bitmapWidth, bitmapHeight);

toRight := 100 + floor(bitmapWidth * 1.25);

toBottom := 200 + floor(bitmapHeight * 1.25);

toRight := 100 + bitmapWidth * 5 div 4;

toBottom := 200 + bitmapHeight * 5 div 4;

toRect := SetBounds(100, 200, toRight, toBottom);

// draw the bitmap again

GetRoot():DrawShape(bitmap, {transform: [fromRect,

toRect]});

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Apple Newton Utilities Guide de l'utilisateur Page 543

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