Android实现图片顺时逆时旋转及拖拽显示效果
Android实现图片顺时逆时旋转及拖拽显示效果
1、首先说一下两个类:
Matrix
Class Overview
The Matrix class holds a 3x3 matrix for transforming coordinates. Matrix does not have a constructor, so it must be explicitly initialized using either reset() - to construct an identity matrix, or one of the set..() functions (e.g. setTranslate, setRotate, etc.).
矩阵类拥有3 x3的坐标变换矩阵。没有一个构造函数矩阵,所以它必须显式初始化的使用或重置()-如何构建一个矩阵,或者一个场景……()的功能(例如,setRotate setTranslate等。)Matrix的操作,总共分为translate(平移),rotate(旋转),scale(缩放)和skew(倾斜)四种,每一种变换在Android的API里都提供了set,post和pre三种操作方式,除了translate,其他三种操作都可以指定中心点。set是直接设置Matrix的值,每次set一次,整个Matrix的数组都会变掉。post是后乘,当前的矩阵乘以参数给出的矩阵。可以连续多次使用post,来完成所需的整个变换。
接下来我们用到了两个方法:
平移方法:两个参数分别是要移到的x、y坐标
PointF
Class Overview
PointF holds two float coordinates
PointF有两个浮点坐标我们要用到该类的一个方法:设置点的x和y坐标
首先看一下效果图:
旋转拖拽后
布局很简单在此不再给出!直接看java代码:
[java]- public class MovePictureActivity extends Activity implements OnClickListener {
- private Button button1, button2;
- private ImageView image;
- PointF startPoint = new PointF();// 有两PointF浮坐标
- Matrix matrix = new Matrix();
- @Override
- public void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.main);
- init();
- }
- private void init() {
- button1 = (Button) findViewById(R.id.button1);
- button2 = (Button) findViewById(R.id.button2);
- button1.setOnClickListener(this);
- button2.setOnClickListener(this);
- image = (ImageView) findViewById(R.id.image);
- image.setOnTouchListener(new ImageViewOnTouchListener());// 为image绑上触摸事件监听
- }
- @Override
- public void onClick(View v) {
- switch (v.getId()) {
- case R.id.button1:
- matrix.postRotate(90, image.getWidth() / 2, image.getHeight() / 2);// 顺时针旋转90度,并且以image.getWidth()/2、image.getHeight()/2为中心旋转;
- break;
- case R.id.button2:
- matrix.postRotate(-90, image.getWidth() / 2, image.getHeight() / 2);// 逆时针旋转90度
- break;
- }
- image.setImageMatrix(matrix);
- }
- private class ImageViewOnTouchListener implements OnTouchListener {
- @Override
- public boolean onTouch(View v, MotionEvent event) {
- switch (event.getAction() & MotionEvent.ACTION_MASK) {// 这里取出来的是event.getAction()返回的值的低八位,MotionEvent.ACTION_MASK是255,
- case MotionEvent.ACTION_DOWN:
- startPoint.set(event.getX(), event.getY());
- break;
- case MotionEvent.ACTION_MOVE:// 移动过程,该事件会不断被触发
- float dx = event.getX() - startPoint.x;
- float dy = event.getY() - startPoint.y;
- matrix.postTranslate(dx, dy);
- startPoint.set(event.getX(), event.getY());
- break;
- }
- image.setImageMatrix(matrix);
- return true;
- }
- }
- }
[java]
- image.setOnTouchListener(new ImageViewOnTouchListener());// 为image绑上触摸事件监听
View.OnTouchListener
该接口:Interface definition for a callback to be invoked when a touch event is dispatched to this view. The callback will be invoked before the touch event is given to the view.
接口定义作为一个回调函数被调用时被派遣去触摸事件这一观点。回调函数被调用之前会触摸事件是给你尽情的观看。
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