canvas save and restore 方法
class CavasView extends View{
public CavasView(Context context) {
super(context);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int px = getMeasuredWidth();
int py = getMeasuredHeight();
Paint bgPaint = new Paint();
bgPaint.setColor(Color. BLUE);
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.pic1 );
canvas.drawRect(0, 0, px, py, bgPaint);
canvas.drawBitmap(bitmap, 0, 0, bgPaint);
canvas.save();
canvas.rotate(90, px/2, py/2);
canvas.drawBitmap(bitmap, 0, 0, bgPaint);
Paint linePaint = new Paint();
linePaint.setColor(Color. RED);
canvas.drawLine(px/2, 0, 0, py/2, linePaint);
canvas.drawLine(px/2, 0, px, py/2, linePaint);
canvas.drawLine(px/2, 0, px/2, py, linePaint);
Paint cirlePaint = new Paint();
canvas.drawCircle(px/2 + 100, py/2 + 100, 40, cirlePaint);
canvas.restore();
canvas.drawCircle(px/2 + 100, py/2 + 100, 40, linePaint);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawColor(Color. BLUE);
Paint paint = new Paint();
paint.setColor(Color. GRAY);
paint.setStrokeWidth(2.0f);
paint.setStyle(Paint.Style. STROKE);
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.pic1 );
canvas.drawLine(0, 600, 480, 600, paint);
for( int i=0;50*i<600;i++)
canvas.drawLine(0, 50*i, 480, 50*i, paint);
for( int i=0;50*i<480;i++)
canvas.drawLine(50*i, 0, 50*i, 600, paint);
Matrix matrix = new Matrix();
Camera camera = new Camera();
camera.save();
camera.rotateX(45);
camera.translate(100, 0, 300);
camera.getMatrix(matrix);
camera.restore();
matrix.setRotate(30);
matrix.preTranslate(-240, -300);
matrix.postTranslate(240, 300);
canvas.concat(matrix);
canvas.drawBitmap(bitmap, matrix, null);
//保存canvas到图片
Bitmap xBitmap = Bitmap.createBitmap(480, 640, Bitmap.Config.ARGB_8888 );
Canvas xCanvas = new Canvas(xBitmap);
xCanvas.drawBitmap(bitmap, matrix, null);
xCanvas.drawLine(0, 600, 480, 600, paint);
for( int i=0;50*i<600;i++)
xCanvas.drawLine(0, 50*i, 480, 50*i, paint);
for( int i=0;50*i<480;i++)
xCanvas.drawLine(50*i, 0, 50*i, 600, paint);
xCanvas.save(Canvas. ALL_SAVE_FLAG);
xCanvas.restore();
Log. d("nicholas" , "onDraw" );
File file;
FileOutputStream os = null;
try {
file = new File("/sdcard/1.png" );
if(!file.exists()){
file.createNewFile();
}
os = new FileOutputStream(file);
xBitmap.compress(CompressFormat. PNG, 50, os);
os.flush();
os.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally{
try {
if(os != null)
os.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
❑ save：用来保存Canvas的状态。save之后，可以调用Canvas的平移、放缩、旋转、错切、裁剪等操作。 画布被修改，如果不这样，画布
被旋转，变形了，画上去点线可能不是我们自己想要的，参看本例，旋转后划线
❑ restore：用来恢复Canvas之前保存的状态。防止save后对Canvas执行的操作对后续的绘制有影响。
