怎么将资源图片设置背景图片？

[占占]

public class MyView extends View {

		private static final float MINP = 0.25f;
		private static final float MAXP = 0.75f;

		private Bitmap mBitmap;
		private Canvas mCanvas;
		private Path mPath;
		private Paint mBitmapPaint;

		public MyView(Context c) {
			super(c);
		//	mBitmap = Bitmap.createBitmap(600, 800, Bitmap.Config.ARGB_8888);
                //就是这里，但这种方式没有效果。
			mBitmap = BitmapFactory.decodeResource(this.getResources(), R.drawable.bk18).copy(Bitmap.Config.ARGB_8888, true);

			mCanvas = new Canvas(mBitmap);
			mPath = new Path();
			mBitmapPaint = new Paint(Paint.DITHER_FLAG);
		}

		public void setBitmap(Bitmap bitmap) {
			mBitmap = bitmap;
		}

		@Override
		protected void onSizeChanged(int w, int h, int oldw, int oldh) {
			// super.onSizeChanged(w, h, oldw, oldh);
			if (mBitmap != null) {
				if (mBitmap.getHeight() == w && mBitmap.getWidth() == h) {
					Log.d(TAG, "rotating bitmap by 90 degree");

					Matrix mtx = new Matrix();
					mtx.postRotate(90, h / 2, w / 2);
					mBitmap = Bitmap.createBitmap(mBitmap, 0, 0, h, w, mtx,
							false);
					mCanvas = new Canvas();
					mCanvas.setBitmap(mBitmap);
					return;
				} else {
					mBitmap.recycle();
				}
			}
			mCanvas = new Canvas();
		//	mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
                        mBitmap = BitmapFactory.decodeResource(this.getResources(), R.drawable.bk18).copy(Bitmap.Config.ARGB_8888, true);
			mCanvas.setBitmap(mBitmap);
		}

		@Override
		protected void onDraw(Canvas canvas) {
			canvas.drawColor(0xFFAAAAAA);

			canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);

			canvas.drawPath(mPath, mPaint);
		}

		private float mX, mY;
		private static final float TOUCH_TOLERANCE = 4;

		private void touch_start(float x, float y) {
			mPath.reset();
			mPath.moveTo(x, y);
			mX = x;
			mY = y;
		}

		private void touch_move(float x, float y) {
			float dx = Math.abs(x - mX);
			float dy = Math.abs(y - mY);
			if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
				mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
				mX = x;
				mY = y;
			}
		}

		private void touch_up() {
			mPath.lineTo(mX, mY);
			// commit the path to our offscreen
			mCanvas.drawPath(mPath, mPaint);
			// kill this so we don't double draw
			mPath.reset();
		}

		void save() {
			myAsyncTask = new MyAsyncTask(mCanvas, mBitmap, fingerPaint.this);
			myAsyncTask.execute(0);
		}

		@Override
		public boolean onTouchEvent(MotionEvent event) {
			float x = event.getX();
			float y = event.getY();

			switch (event.getAction()) {
			case MotionEvent.ACTION_DOWN:
				touch_start(x, y);
				invalidate();
				break;
			case MotionEvent.ACTION_MOVE:
				touch_move(x, y);
				invalidate();
				break;
			case MotionEvent.ACTION_UP:
				touch_up();
				invalidate();
				break;
			}
			return true;
		}
	}

大家看看。

[占占]

没人么，自顶一个。

[褚六]

在XML文件中设置android:background属性 || 在Activity程序中使用setBackgroundResource()方法

[占占]

首先非常感谢你的回答，你说的那个方法我试了。是可以设置背景图片。但现在情况是这样，我最终还是需要获得一个bitmap对象，然后将其通过canvas的构造方法去构造一个画布，然后在再其上面涂鸦。可是，我用了好几种将资源文件转为bitmap的方法并传入都会报错。 包括：BitmapFactory.decodeResource、this.getResources().getDrawable等。。 报错如下：java.lang.RuntimeException: Unable to start activity ComponentInfo{com.llm.android.fingerPaint/com.llm.android.fingerPaint.fingerPaint}: java.lang.IllegalStateException: Immutable bitmap passed to Canvas constructor

[顾小林]

setBackgroundResource(int) 直接调用这个方法 或者 之类的方法

[wowowowo]

Bitmap bitmaptemp = ((BitmapDrawable) context.getResources().getDrawable(resId)).getBitmap();

[穿裤衩闯天下]

你试试我的这个方法，我这样是可以设置的，因为我这个是用一个小的图片来平铺的，所以写了有两个循环来横向和纵向平铺，如果你的图片够大的话，那两个方法可以不用！

    /**
     * @param bitmap 设置涂鸦板的背景
     */
    public void setGraffitiBg(Bitmap bitmap) {

        mGraffitiPadBg = Bitmap.createBitmap(screenInfo.getScreenWidth(),
                screenInfo.getScreenHeight(), Bitmap.Config.ARGB_8888);

        mCanvas = new Canvas(mGraffitiPadBg);

        if (bitmap == null) {
            /*
			 * 设置画布的颜色，当使用图片为背景时不能设置，否则会覆盖图片
			 */
            // mCanvas.drawColor(getResources().getColor(android.R.color.darker_gray));
			/*
			 * 设置默认背景图片
			 */
            Bitmap defaultbg = BitmapFactory.decodeResource(getResources(),
                    R.drawable.huise1);
            mCanvas.drawBitmap(drawColTilebitmap(drawRowTileBitmap(defaultbg)),
                    0, 0, mPaint);
        } else {

        }
    }
/**
     * @param bitmap
     * @return 横向平铺背景图片
     */
    private Bitmap drawRowTileBitmap(Bitmap bitmap) {
        int count = (screenInfo.getScreenWidth() + bitmap.getWidth() - 1)
                / bitmap.getWidth();

        Bitmap rowTileBitmap = Bitmap.createBitmap(screenInfo.getScreenWidth(),
                bitmap.getHeight(), Config.ARGB_8888);

        Canvas rowCanvas = new Canvas(rowTileBitmap);
        for (int idx = 0; idx < count; idx++) {
            rowCanvas.drawBitmap(bitmap, bitmap.getWidth() * idx, 0, null);
        }

        return rowTileBitmap;

    }

    /**
     * @param bitmap
     * @return 纵向平铺背景图片
     */
    private Bitmap drawColTilebitmap(Bitmap bitmap) {
        int count = (screenInfo.getScreenHeight() + bitmap.getHeight() - 1)
                / bitmap.getHeight();
        Bitmap colTileBitmap = Bitmap.createBitmap(bitmap.getWidth(),
                screenInfo.getScreenHeight(), Config.ARGB_8888);
        Canvas colCanvas = new Canvas(colTileBitmap);
        for (int idx = 0; idx < count; idx++) {
            colCanvas.drawBitmap(bitmap, 0, bitmap.getHeight() * idx, null);
        }

        return colTileBitmap;
    }