如何在Android中将缩放，拖动和旋转应用于图像 [英] How to apply zoom, drag and rotation to an image in Android

问题描述

有人可以告诉我该教程在Android应用程序中对图像进行缩放，拖动和旋转吗?

Can somebody tell me the tutorial to apply zoom, drag and rotate on an image in android application?

推荐答案

尝试以下代码对我有用.

Try with below code its working for me.

    float[] lastEvent = null;
    float d = 0f;
    float newRot = 0f;
    private Matrix matrix = new Matrix();
    private Matrix savedMatrix = new Matrix();
    public static String fileNAME;
    public static int framePos = 0;

    private float scale = 0;
    private float newDist = 0;

    // Fields
    private String TAG = this.getClass().getSimpleName();

    // We can be in one of these 3 states
    private static final int NONE = 0;
    private static final int DRAG = 1;
    private static final int ZOOM = 2;
    private int mode = NONE;

    // Remember some things for zooming
    private PointF start = new PointF();
    private PointF mid = new PointF();
    float oldDist = 1f;

     public boolean onTouch(View v, MotionEvent event) {
                ImageView view = (ImageView) v;

                // Handle touch events here...
                switch (event.getAction() & MotionEvent.ACTION_MASK) {
                case MotionEvent.ACTION_DOWN:
                    savedMatrix.set(matrix);
                    start.set(event.getX(), event.getY());
                    mode = DRAG;
                    lastEvent = null;
                    break;
                case MotionEvent.ACTION_POINTER_DOWN:
                    oldDist = spacing(event);
                    if (oldDist > 10f) {
                        savedMatrix.set(matrix);
                        midPoint(mid, event);
                        mode = ZOOM;
                    }
                    lastEvent = new float[4];
                    lastEvent[0] = event.getX(0);
                    lastEvent[1] = event.getX(1);
                    lastEvent[2] = event.getY(0);
                    lastEvent[3] = event.getY(1);
                    d = rotation(event);
                    break;
                case MotionEvent.ACTION_UP:
                case MotionEvent.ACTION_POINTER_UP:
                    mode = NONE;
                    lastEvent = null;
                    break;
                case MotionEvent.ACTION_MOVE:
                    if (mode == DRAG) {
                        // ...
                        matrix.set(savedMatrix);
                        matrix.postTranslate(event.getX() - start.x, event.getY()
                                - start.y);
                    } else if (mode == ZOOM && event.getPointerCount() == 2) {
                        float newDist = spacing(event);
                        matrix.set(savedMatrix);
                        if (newDist > 10f) {
                            float scale = newDist / oldDist;
                            matrix.postScale(scale, scale, mid.x, mid.y);
                        }
                        if (lastEvent != null) {
                            newRot = rotation(event);
                            float r = newRot - d;
                            matrix.postRotate(r, view.getMeasuredWidth() / 2,
                                    view.getMeasuredHeight() / 2);
                        }
                    }
                    break;
                }

                view.setImageMatrix(matrix);

                return true;
            }

//用于在多点触控上旋转图像.

//For rotate image on multi-touch.

private float rotation(MotionEvent event) {
        double delta_x = (event.getX(0) - event.getX(1));
        double delta_y = (event.getY(0) - event.getY(1));
        double radians = Math.atan2(delta_y, delta_x);

        return (float) Math.toDegrees(radians);
    }
private float spacing(MotionEvent event) {
        float x = event.getX(0) - event.getX(1);
        float y = event.getY(0) - event.getY(1);
        return FloatMath.sqrt(x * x + y * y);
    }

private void midPoint(PointF point, MotionEvent event) {
        float x = event.getX(0) + event.getX(1);
        float y = event.getY(0) + event.getY(1);
        point.set(x / 2, y / 2);
    }

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