在我的 android 应用程序中，我有一个裁剪图像。因此，我将自定义 View 编程为我的裁剪框。我可以移动裁剪框。但我的问题是如何拖动裁剪框的边框并更改它的宽度和高度。我该怎么做？

属性类:

public class Attr {

    public static final float CROP_BOX_START_X = 5;
    public static final float CROP_BOX_START_Y = 5;
    public static final float CROP_BOX_END_X = 305;
    public static final float CROP_BOX_END_Y = 105;

}

裁剪框类:

public class CropBox extends View {

    private Paint paint = new Paint();


    public CropBox(Context context) {
        super(context);
    }

    public CropBox(Context context, AttributeSet attributeSet) {
        super(context, attributeSet);
    }


    @Override
    public void onDraw(Canvas canvas) {
        float[][] circleXY = {
            {Attr.CROP_BOX_START_X, Attr.CROP_BOX_START_Y},
            {(Attr.CROP_BOX_START_X + Attr.CROP_BOX_END_X) / 2, Attr.CROP_BOX_START_Y},
            {Attr.CROP_BOX_END_X, Attr.CROP_BOX_START_Y},
            {Attr.CROP_BOX_START_X, Attr.CROP_BOX_END_Y},
            {(Attr.CROP_BOX_START_X + Attr.CROP_BOX_END_X) / 2, Attr.CROP_BOX_END_Y},
            {Attr.CROP_BOX_END_X, Attr.CROP_BOX_END_Y},
            {Attr.CROP_BOX_START_X, (Attr.CROP_BOX_START_Y + Attr.CROP_BOX_END_Y) / 2},
            {Attr.CROP_BOX_END_X, (Attr.CROP_BOX_START_Y + Attr.CROP_BOX_END_Y) / 2}
        };
        float[][] lineXY = {
            {Attr.CROP_BOX_START_X, Attr.CROP_BOX_START_Y, Attr.CROP_BOX_END_X, Attr.CROP_BOX_START_Y},
            {Attr.CROP_BOX_START_X, Attr.CROP_BOX_END_Y, Attr.CROP_BOX_END_X, Attr.CROP_BOX_END_Y},
            {Attr.CROP_BOX_START_X, Attr.CROP_BOX_START_Y, Attr.CROP_BOX_START_X, Attr.CROP_BOX_END_Y},
            {Attr.CROP_BOX_END_X, Attr.CROP_BOX_START_Y, Attr.CROP_BOX_END_X, Attr.CROP_BOX_END_Y}
        };

        paint.setColor(Color.CYAN);
        paint.setStrokeWidth(1);

        for(int i = 0 ; i < circleXY.length ; i++)
            canvas.drawCircle(circleXY[i][0], circleXY[i][1], 5, paint);

        paint.setStrokeWidth(2);

        for(int i = 0 ; i < lineXY.length ; i++)
            canvas.drawLine(lineXY[i][0], lineXY[i][2], lineXY[i][2], lineXY[i][3], paint);
    }

}

CropTestActivity 类:

public class CropTestActivity extends Activity {

    private ImageView imageView;
    private CropBox cropBox;
    private RelativeLayout relativeLayout;
    private RelativeLayout.LayoutParams layoutParams;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.crop_test_layout);
        imageView = (ImageView)findViewById(R.id.android_image);
        cropBox = new CropBox(this);
        relativeLayout = (RelativeLayout)findViewById(R.id.crop_test_layout);
        layoutParams = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.FILL_PARENT, RelativeLayout.LayoutParams.FILL_PARENT);
        imageView.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
            public void onGlobalLayout() {
                imageView.getViewTreeObserver().removeGlobalOnLayoutListener(this);
                layoutParams.leftMargin = imageView.getWidth() / 2 - (int)((Attr.CROP_BOX_START_X + Attr.CROP_BOX_END_X) / 2) + imageView.getLeft();
                layoutParams.topMargin = imageView.getHeight() / 2 - (int)((Attr.CROP_BOX_START_Y + Attr.CROP_BOX_END_Y) / 2) + imageView.getTop();
            }
        });
        relativeLayout.addView(cropBox, layoutParams);
        cropBox.setOnTouchListener(new Crop(imageView));
    }

}

裁剪等级:

public class Crop implements OnTouchListener {

    private static final int NONE = 0;
    private static final int BOX_DRAG = 1;
    private static final int BORDER_DRAG = 2;

    private int mode = NONE;

    private float cropBoxStartX = Attr.CROP_BOX_START_X;
    private float cropBoxStartY = Attr.CROP_BOX_START_Y;
    private float cropBoxEndX = Attr.CROP_BOX_END_X;
    private float cropBoxEndY = Attr.CROP_BOX_END_Y;

    private ImageView imageView;

    private PointF start = new PointF();


    public Crop(ImageView imageView) {
        this.imageView = imageView;
    }


    public boolean onTouch(View view, MotionEvent event) {
        RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams)view.getLayoutParams();

        switch(event.getAction() & MotionEvent.ACTION_MASK) {

            case MotionEvent.ACTION_DOWN:
                start.set(event.getX(), event.getY());
                if(event.getX() > cropBoxStartX && event.getX() < cropBoxEndX && event.getY() > cropBoxStartY && event.getY() < cropBoxEndY)
                    mode = BOX_DRAG;
                else if(event.getX() == cropBoxStartX || event.getX() == cropBoxEndX || event.getY() == cropBoxStartY || event.getY() == cropBoxEndY)
                    mode = BORDER_DRAG;
                else
                    mode = NONE;
                break;

            case MotionEvent.ACTION_UP:
                mode = NONE;
                break;

            case MotionEvent.ACTION_MOVE:
                if(mode == BOX_DRAG) {
                    layoutParams.leftMargin = (int)event.getX() - (int)start.x + view.getLeft();
                    layoutParams.topMargin = (int)event.getY() - (int)start.y + view.getTop();
                    while(layoutParams.topMargin + 5 < imageView.getTop())
                        layoutParams.topMargin++;
                    while(layoutParams.leftMargin + (cropBoxEndX - cropBoxStartX + 5) > imageView.getRight())
                        layoutParams.leftMargin--;
                    while(layoutParams.topMargin + (cropBoxEndY - cropBoxStartY + 5) > imageView.getBottom())
                        layoutParams.topMargin--;
                    while(layoutParams.leftMargin + 5 < imageView.getLeft())
                        layoutParams.leftMargin++;
                }
                else if(mode == BORDER_DRAG) {
                }
                break;
        }
        view.setLayoutParams(layoutParams);
        return true;
    }

}

布局 XML:

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/crop_test_layout"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <ImageView
        android:id="@+id/android_image"
        android:src="@drawable/android"
        android:layout_width="fill_parent"
        android:layout_height="300dp"
        android:layout_marginTop="10dp"
        android:layout_marginRight="10dp"
        android:layout_marginBottom="10dp"
        android:layout_marginLeft="10dp"
        android:layout_gravity="center"
        android:scaleType="fitXY"
        android:contentDescription="@string/android_image_description" >
    </ImageView>

</RelativeLayout>

调整大小之前:

调整大小后:

感谢您的帮助。

最佳答案

解决方案如下，

从 Activity 修改 onCreate

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.crop_test_layout);
    imageView = (ImageView)findViewById(R.id.android_image);
    cropBox = new CropBox(this, imageView);
    relativeLayout = (RelativeLayout)findViewById(R.id.crop_test_layout);
    relativeLayout.addView(cropBox);
}

修改后的 CropBox 类:

public class CropBox extends View {

    private static final int CROP_BOX_START_X = 5;
    private static final int CROP_BOX_START_Y = 5;
    private static final int CROP_BOX_END_X = 305;
    private static final int CROP_BOX_END_Y = 105;

    private static final int DRAG_SQUARE = 75;

    public ImageView mImageView;
    boolean mIsFirstClick = false;

    private Paint paint = new Paint();
    private Rect mRect;

    public CropBox(Context context, ImageView aBaseView) {
        super(context);
        mImageView = aBaseView;
        mRect = new Rect(CROP_BOX_START_X, CROP_BOX_START_Y, CROP_BOX_END_X, CROP_BOX_END_Y);
        setOnTouchListener(new Crop());
    }

    public CropBox(Context context, AttributeSet attributeSet) {
        super(context, attributeSet);
    }

    @Override
    public void onDraw(Canvas canvas) {

        paint.setStrokeWidth(2);

        paint.setColor(Color.CYAN);
        paint.setStyle(Paint.Style.STROKE);

        canvas.drawRect(mRect, paint);

        canvas.drawLine(mRect.right-DRAG_SQUARE, mRect.bottom-DRAG_SQUARE, 
                mRect.right, mRect.bottom-DRAG_SQUARE, paint);

        canvas.drawLine(mRect.right-DRAG_SQUARE, mRect.bottom-DRAG_SQUARE, 
                mRect.right-DRAG_SQUARE, mRect.bottom, paint);
    }

    class Crop implements OnTouchListener {

        private static final int NONE = 0;
        private static final int BOX_DRAG = 1;
        private static final int BORDER_DRAG = 2;

        private int mode = NONE;

        private PointF start = new PointF();

        public boolean onTouch(View view, MotionEvent event) {
            RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams)view.getLayoutParams();

            switch(event.getAction() & MotionEvent.ACTION_MASK) {

                case MotionEvent.ACTION_DOWN:
                    start.set(event.getX(), event.getY());

                    if((event.getX() <= mRect.right && event.getX() >=(mRect.right - DRAG_SQUARE)) 
                            && (event.getY() >= mRect.top && event.getY() >=(mRect.bottom - DRAG_SQUARE))){
                        mode = BORDER_DRAG;
                        mIsFirstClick = false;
                    }
                    else if(mRect.contains((int)event.getX(), (int)event.getY())) {
                        mode = BOX_DRAG;
                        if (mIsFirstClick){
                            mRect = new Rect(CROP_BOX_START_X, CROP_BOX_START_Y, 
                                    CROP_BOX_END_X, CROP_BOX_END_Y);
                            mIsFirstClick = false;  
                        } else {
                            mIsFirstClick = true;   
                        }
                    }
                    else{
                        mode = NONE;
                        mIsFirstClick = true;
                    }
                    break;

                case MotionEvent.ACTION_UP:
                    mode = NONE;
                    break;

                case MotionEvent.ACTION_MOVE:
                    mIsFirstClick = false;
                    if(mode == BOX_DRAG) {
                        layoutParams.leftMargin = (int)event.getX() - (int)start.x + view.getLeft();
                        layoutParams.topMargin = (int)event.getY() - (int)start.y + view.getTop();
                    }
                    else if(mode == BORDER_DRAG) {
                        if (event.getX() > view.getLeft() && event.getY() > view.getTop()){
                            mRect.right = (int) event.getX();
                            mRect.bottom = (int) event.getY();
                        }
                    }
                    while(layoutParams.topMargin + 5 < mImageView.getTop())
                        layoutParams.topMargin++;
                    while(layoutParams.leftMargin + mRect.right > mImageView.getRight())
                        layoutParams.leftMargin--;
                    while(layoutParams.topMargin + mRect.bottom > mImageView.getBottom())
                        layoutParams.topMargin--;
                    while(layoutParams.leftMargin + 5 < mImageView.getLeft())
                        layoutParams.leftMargin++;
                    break;
            }
            view.setLayoutParams(layoutParams);
            invalidate();
            return true;
        }
    }
}

我想提几点。

• 在 CropBox 中合并 Attr 和 Crop
• 无需从线条创建矩形。您可以使用 Rect。
• 切勿在 Draw 方法中初始化数组/对象
• 添加了一个功能:如果在矩形上双击它会返回到原来的位置
• 在 ImageView 中限制矩形可能会有一些问题。我相信您可以解决这些问题...:)

除此之外，还有另一种使用 Canvas 缩放的有趣方式 Image in Canvas with touch events 使用该类而不是 Cropbox 并尝试一下。

希望对你有帮助..

关于java - 在 Android 中更改自定义 View 的宽度和高度，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12230371/