android 二维码扫描(zxing使用小结)

最新推荐文章于 2021-05-26 05:45:25 发布

转载最新推荐文章于 2021-05-26 05:45:25 发布 · 1.1k 阅读

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本文详细介绍了如何优化二维码扫描应用的界面展示效果，包括调整扫描框位置以适应不同屏幕布局，解决扫描框内图片变形问题，并优化了界面绘制流程。通过设置全屏模式来消除扫描框与二维码之间的视觉偏差，同时通过CameraManager.java中的getFramingRect()方法灵活调整扫描框大小和位置。此外，通过CameraConfigurationManager.java中的setDesiredCameraParameters方法确保预览图片正确显示，避免图片失真。

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主要有三点：

1、界面绘制，包括4个边角、上下滚动的横线、在画布上添加文字

2、调整二维码扫描框的位置。

3、解决图片被压变形的问题。

1、界面绘制

ViewfinderView.java中onDraw()方法

@Override
    public
void onDraw(Canvas canvas) {
        // 中间的扫描框，你要修改扫描框的大小，去CameraManager里面修改
        Rect frame = CameraManager.get().getFramingRect();
        int
top = frame.top;
        int
left = frame.left;
        int
right = frame.right;
        int
bottom = frame.bottom;
        frame =
new Rect(left , top, right , bottom );
        // 初始化中间线滑动的最上边和最下边
        if
(!isFirst) {
            isFirst =
true;
            slideTop = frame.top;
            slideBottom = frame.bottom;
        }
 
        // 获取屏幕的宽和高
        int
width = canvas.getWidth();
        int
height = canvas.getHeight();
 
        // 画出扫描框外面的阴影部分，共四个部分，扫描框的上面到屏幕上面，扫描框的下面到屏幕下面
        // 扫描框的左边面到屏幕左边，扫描框的右边到屏幕右边
        // Draw the exterior (i.e. outside the framing rect) darkened
        paint.setColor(resultBitmap !=
null ? resultColor : maskColor);
        canvas.drawRect(0,
0, width, frame.top, paint);
        canvas.drawRect(0, frame.top, frame.left, frame.bottom +
1, paint);
        canvas.drawRect(frame.right +
1, frame.top, width, frame.bottom +
1,
                paint);
        canvas.drawRect(0, frame.bottom +
1, width, height, paint);
 
        if
(resultBitmap != null) {
            // Draw the opaque result bitmap over the scanning rectangle
            paint.setAlpha(OPAQUE);
            canvas.drawBitmap(resultBitmap, frame.left, frame.top, paint);
        }
else {
            // 画扫描框边上的角，总共8个部分
            paint.setColor(Color.GREEN);
            canvas.drawRect(frame.left, frame.top, frame.left + ScreenRate,
                    frame.top + CORNER_WIDTH, paint);
            canvas.drawRect(frame.left, frame.top, frame.left + CORNER_WIDTH, frame.top
                    + ScreenRate, paint);
            canvas.drawRect(frame.right - ScreenRate, frame.top, frame.right,
                    frame.top + CORNER_WIDTH, paint);
            canvas.drawRect(frame.right - CORNER_WIDTH, frame.top, frame.right, frame.top
                    + ScreenRate, paint);
            canvas.drawRect(frame.left, frame.bottom - CORNER_WIDTH, frame.left
                    + ScreenRate, frame.bottom, paint);
            canvas.drawRect(frame.left, frame.bottom - ScreenRate,
                    frame.left + CORNER_WIDTH, frame.bottom, paint);
            canvas.drawRect(frame.right - ScreenRate, frame.bottom - CORNER_WIDTH,
                    frame.right, frame.bottom, paint);
            canvas.drawRect(frame.right - CORNER_WIDTH, frame.bottom - ScreenRate,
                    frame.right, frame.bottom, paint);
             
            //绘制中间的线,每次刷新界面，中间的线往下移动SPEEN_DISTANCE
             
            slideTop += SPEEN_DISTANCE;
            if(slideTop >= frame.bottom){
                slideTop = frame.top;
            }
            Rect lineRect =
new Rect();  
            lineRect.left = frame.left; 
            lineRect.right = frame.right; 
            lineRect.top = slideTop; 
            lineRect.bottom = slideTop +
18;  
            canvas.drawBitmap(((BitmapDrawable)(getResources().getDrawable(R.drawable.qrcode_scan_line))).getBitmap(),
null, lineRect, paint);
             
            //画扫描框下面的字
//            paint.setColor(Color.WHITE);   
//            paint.setTextSize(TEXT_SIZE * density);   
//            paint.setAlpha(0x40);   
//            paint.setTypeface(Typeface.create(System, Typeface.BOLD));  
//            String text = 将二维码放入框内, 即可自动扫描; 
//            float textWidth = paint.measureText(text); 
//             
//            canvas.drawText(text, (width - textWidth)/2, (float) (frame.bottom + (float)TEXT_PADDING_TOP *density), paint);
             
             
 
            Collection<resultpoint> currentPossible = possibleResultPoints;
            Collection<resultpoint> currentLast = lastPossibleResultPoints;
            if
(currentPossible.isEmpty()) {
                lastPossibleResultPoints =
null;
            }
else {
                possibleResultPoints =
new HashSet<resultpoint>(5);
                lastPossibleResultPoints = currentPossible;
                paint.setAlpha(OPAQUE);
                paint.setColor(resultPointColor);
                for
(ResultPoint point : currentPossible) {
                    canvas.drawCircle(frame.left + point.getX(), frame.top
                            + point.getY(),
6.0f, paint);
                }
            }
            if
(currentLast != null) {
                paint.setAlpha(OPAQUE /
2);
                paint.setColor(resultPointColor);
                for
(ResultPoint point : currentLast) {
                    canvas.drawCircle(frame.left + point.getX(), frame.top
                            + point.getY(),
3.0f, paint);
                }
            }
 
             
            //只刷新扫描框的内容，其他地方不刷新
            postInvalidateDelayed(ANIMATION_DELAY, frame.left, frame.top,
                    frame.right, frame.bottom);
             
        }
    }</resultpoint></resultpoint></resultpoint>

2、调整位置

如果不设置全屏，扫描框的位置和取图的位置高度目测会有50px误差，不全屏公式：((Y - 标题栏 - 状态栏)/2 - 扫描框高度)/2 = y轴坐标只要不全屏：就会有误差，导致框中的二维码靠上或者远离二维码才会扫描成功如果设置为全屏，就不会有误差，请了解内情的大神告知笔者，想知道什么原因造成 CameraManager.java 中 getFramingRect()方法

public 
Rect getFramingRect() {
    Point screenResolution = configManager.getScreenResolution();
    if
(framingRect == null) {
      if
(camera == null) {
        return
null;
      }
      /* 确定在固定比例分辨率下二维码扫描框的宽高*/ 
      int
width = screenResolution.x * 3
/ 4;
      if
(width < MIN_FRAME_WIDTH) {
        width = MIN_FRAME_WIDTH;
      }
else if
(width > MAX_FRAME_WIDTH) {
        width = MAX_FRAME_WIDTH;
      }
      int
height = screenResolution.y * 3
/ 4;
      if
(height < MIN_FRAME_HEIGHT) {
        height = MIN_FRAME_HEIGHT;
      }
else if
(height > MAX_FRAME_HEIGHT) {
        height = MAX_FRAME_HEIGHT;
      }
      //计算x轴y轴坐标,可在此调整二维码框的位置
      int
leftOffset = (screenResolution.x - width) / 2
;
      int
topOffset = ((screenResolution.y) /2
- height) / 2 
;
      framingRect =
new Rect(leftOffset, topOffset, leftOffset + width, topOffset + height);
      Log.d(TAG, Calculated framing rect:  + framingRect);
    }
    return
framingRect;
  }

3、框中图片变形

CameraConfigurationManager.java中void setDesiredCameraParameters(Camera camera)方法

/**
     * Sets the camera up to take preview images which are used for both preview
     * and decoding. We detect the preview format here so that
     * buildLuminanceSource() can build an appropriate LuminanceSource subclass.
     * In the future we may want to force YUV420SP as it's the smallest, and the
     * planar Y can be used for barcode scanning without a copy in some cases.
     */
    void
setDesiredCameraParameters(Camera camera) {
        // Camera.Parameters parameters = camera.getParameters();
        // Log.d(TAG, Setting preview size:  + cameraResolution);
        // parameters.setPreviewSize(cameraResolution.x, cameraResolution.y);
        // setFlash(parameters);
        // setZoom(parameters);
        // //setSharpness(parameters);
        // //modify here
        // camera.setDisplayOrientation(90);
        // camera.setParameters(parameters);
        Camera.Parameters parameters = camera.getParameters();
        List<size> supportedPreviewSizes = parameters
                .getSupportedPreviewSizes();
        int
position = 0;
        if
(supportedPreviewSizes.size() > 2) {
            position = supportedPreviewSizes.size() /
2 + 1;// supportedPreviewSizes.get();
        }
else {
            position = supportedPreviewSizes.size() /
2;
        }
 
        int
width = supportedPreviewSizes.get(position).width;
        int
height = supportedPreviewSizes.get(position).height;
        Log.d(TAG, Setting preview size:  + cameraResolution);
        camera.setDisplayOrientation(90);
        cameraResolution.x = width;
        cameraResolution.y = height;
        parameters.setPreviewSize(width, height);
        setFlash(parameters);
        setZoom(parameters);
        // setSharpness(parameters);
        camera.setParameters(parameters);
    }</size>