41 lines
1.3 KiB
JavaScript
41 lines
1.3 KiB
JavaScript
/** Changes the zoom level of the canvas
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* @param {*} direction 'in' or 'out'
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* @param {*} cursorLocation The position of the cursor when the user zoomed
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*/
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function changeZoom (direction, cursorLocation) {
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// Computing current width and height
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var oldWidth = canvasSize[0] * zoom;
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var oldHeight = canvasSize[1] * zoom;
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var newWidth, newHeight;
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//change zoom level
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//if you want to zoom out, and the zoom isnt already at the smallest level
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if (direction == 'out' && zoom > 1) {
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zoom -= Math.ceil(zoom / 10);
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newWidth = canvasSize[0] * zoom;
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newHeight = canvasSize[1] * zoom;
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//adjust canvas position
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layers[0].setCanvasOffset(
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layers[0].canvas.offsetLeft + (oldWidth - newWidth) * cursorLocation[0]/oldWidth,
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layers[0].canvas.offsetTop + (oldHeight - newHeight) * cursorLocation[1]/oldWidth);
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}
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//if you want to zoom in
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else if (direction == 'in' && zoom + Math.ceil(zoom/10) < window.innerHeight/4){
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zoom += Math.ceil(zoom/10);
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newWidth = canvasSize[0] * zoom;
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newHeight = canvasSize[1] * zoom;
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//adjust canvas position
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layers[0].setCanvasOffset(
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layers[0].canvas.offsetLeft - Math.round((newWidth - oldWidth)*cursorLocation[0]/oldWidth),
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layers[0].canvas.offsetTop - Math.round((newHeight - oldHeight)*cursorLocation[1]/oldHeight));
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}
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//resize canvas
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layers[0].resize();
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// adjust brush size
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currentTool.updateCursor();
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}
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