您可以在隐藏的画布中绘制整个地图(通常只是相对静态的背景,而不是动画!),然后将您需要的部分复制到可见的画布上:
final Canvas hiddenCanvas = buildCanvas(1000, 1000);
drawHexPattern(hiddenCanvas);
// don't add the hiddenCanvas to your DOM
final Canvas visibleCanvas = buildCanvas(320, 200);
RootPanel.get().add(visibleCanvas); // add the visibleCanvas to the DOM
showArea(hiddenCanvas, visibleCanvas, 0, 0);
...
showArea(hiddenCanvas, visibleCanvas, 20, 10);
...
使用showArea()
类似的方法
private void showArea(final Canvas hiddenCanvas, final Canvas visibleCanvas,
final double x, final double y) {
final Context2d hiddenCtx = hiddenCanvas.getContext2d();
final Context2d visibleCtx = visibleCanvas.getContext2d();
final ImageData imageData = hiddenCtx.getImageData(x, y,
visibleCanvas.getCoordinateSpaceWidth(),
visibleCanvas.getCoordinateSpaceHeight());
visibleCtx.putImageData(imageData, 0, 0);
}
我用一个工作示例创建了一个 pastebin:http: //pastebin.com/tPN2093a