osmand中矢量数据地图绘制

代码版本为1.0.0.

参考MapVectorLayer.java

重载了Layer的onDraw

public void onDraw(Canvas canvas, RectF latLonBounds, RectF tilesRect, DrawSettings drawSettings) {
if (!visible) {
return;
}
if (!isVectorDataVisible() && tileLayer != null) {
tileLayer.drawTileMap(canvas, tilesRect);
resourceManager.getRenderer().interruptLoadingMap();
} else {
if (!view.isZooming()) {
pixRect.set(0, 0, view.getWidth(), view.getHeight());
updateRotatedTileBox();
if (resourceManager.updateRenderedMapNeeded(rotatedTileBox, drawSettings)) {
// pixRect.set(-view.getWidth(), -view.getHeight() / 2, 2 * view.getWidth(), 3 * view.getHeight() / 2);
pixRect.set(-view.getWidth() / 3, -view.getHeight() / 4, 4 * view.getWidth() / 3, 5 * view.getHeight() / 4);
updateRotatedTileBox();
resourceManager.updateRendererMap(rotatedTileBox);
}

}

MapRenderRepositories renderer = resourceManager.getRenderer();
drawRenderedMap(canvas, renderer.getBitmap(), renderer.getBitmapLocation());
drawRenderedMap(canvas, renderer.getPrevBitmap(), renderer.getPrevBmpLocation());
}
}

在onDraw中。具体的描画是调用的两次drawRenderedMap

共有两个bitmap。renderer.getBitmap()用于保存当前描绘内容，renderer.getPrevBitmap()用于保存之前状态的描绘内容。

通过这两个bitmap，来完成挪动地图的效果及zoom的效果。

分析一下bitmap的贴图算法

private boolean drawRenderedMap(Canvas canvas, Bitmap bmp, RotatedTileBox bmpLoc) {
boolean shown = false;
if (bmp != null && bmpLoc != null) {
float rot = bmpLoc.getRotate();//取得图片的选择角度
float mult = (float) MapUtils.getPowZoom(view.getZoom() - bmpLoc.getZoom());//view的zoom与bmp的zoom间的缩放倍数
float fmult = (float) MapUtils.getPowZoom(view.getFloatZoom() - bmpLoc.getZoom());//缩放动画中的过渡float zoom

float tx = view.getXTile() / mult;//将view的tile坐标转到bmp的tile坐标
float ty = view.getYTile() / mult;
float dleftX1 = bmpLoc.getLeftTileX() - tx;//取得图片左上与屏幕中心的差值距离
float dtopY1 = bmpLoc.getTopTileY() - ty;

float ts = view.getSourceTileSize() * fmult;//tile size进行缩放

float cos = bmpLoc.getRotateCos();
float sin = bmpLoc.getRotateSin();
float x1 = MapUtils.calcDiffPixelX(sin, cos, dleftX1, dtopY1, ts) + view.getCenterPointX();//计算屏幕坐标
float y1 = MapUtils.calcDiffPixelY(sin, cos, dleftX1, dtopY1, ts) + view.getCenterPointY();

canvas.rotate(-rot, view.getCenterPointX(), view.getCenterPointY());//将画布反向旋转。这是在父控件中canvas会rotate一个角度。这里做一个旋转的差值校正
　　　　　　　//设置贴图位置
destImage.set(x1, y1, x1 + bmpLoc.getTileWidth() * ts, y1 +
bmpLoc.getTileHeight() * ts);
if(!bmp.isRecycled()){
canvas.drawBitmap(bmp, null, destImage, paintImg);
shown = true;
}
canvas.rotate(rot, view.getCenterPointX(), view.getCenterPointY());
}
return shown;
}