Android 自定义可拖拽，可放大缩小的ImageView
最近需要开发控件，需要放大缩小可随意拖拽，于是就自定义View来实现，具体如下：
案例：
1.自定义View
import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.view.MotionEvent;
import android.view.View;
public class ZoomDragImageView extends View {
private Context mContext;
private float mRation_WH = 0;
private float mLastX = 0;
private float mLastY = 0;
private double mDoubleOne;
private Paint mZoomPaint;
private Drawable mZoomDrawable;
private Rect mZoomDrawableRect = new Rect();
private boolean isFirst = true;
private int SINGALDOWN = 1;// 单点按下
private int MUTILDOWM = 2;// 双点按下
private int MUTILMOVE = 3;// 双点拖拽
private int mCurStatus = 0;
public ZoomDragImageView(Context context) {
super(context);
this.mContext = context;
mZoomPaint = new Paint();
mZoomPaint.setAntiAlias(true);
mZoomPaint.setColor(Color.BLACK);
mZoomPaint.setStyle(Paint.Style.FILL);
mZoomPaint.setTextSize(35.0f);
}
@SuppressLint("DrawAllocation")
@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
if (mZoomDrawable == null || mZoomDrawable.getIntrinsicHeight() == 0
|| mZoomDrawable.getIntrinsicWidth() == 0) {
return;
}
setBackground();
mZoomDrawable.draw(canvas);
}
@SuppressLint("ClickableViewAccessibility")
@Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub
switch (event.getPointerCount()) {
case 1:
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
mCurStatus = SINGALDOWN;
mLastX = event.getX();
mLastY = event.getY();
break;
case MotionEvent.ACTION_UP:
//checkBounds();
break;
case MotionEvent.ACTION_MOVE:
if (mCurStatus == SINGALDOWN) {
int offsetWidth = (int) (event.getX() - mLastX);
int offsetHeight = (int) (event.getY() - mLastY);
int mWidth = mZoomDrawableRect.right-mZoomDrawableRect.left;
int mHeight = mZoomDrawableRect.bottom-mZoomDrawableRect.top;
int left=mZoomDrawableRect.left;
int top = mZoomDrawableRect.top;
int l, r, t, b;
//当水平或者垂直滑动距离大于10,才算是拖动事件
if (Math.abs(offsetWidth) > 10 || Math.abs(offsetHeight) > 10) {
l = (int) (left + offsetWidth);
r = l + mWidth;
t = (int) (top + offsetHeight);
b = t + mHeight;
//边界判断,不让布局滑出界面
if (l < 0) {
l = 0;
r = l + mWidth;
} else if (r > 1920) {
r = 1920;
l = r - mWidth;
}
if (t < 0) {
t = 0;
b = t + mHeight;
} else if (b > 1080) {
b = 1080;
t = b - mHeight;
}
mLastX = event.getX();
mLastY = event.getY();
mZoomDrawableRect.set(l,t,r,b);
invalidate();
}
}
break;
default:
break;
}
break;
default:
switch (event.getAction()) {
case MotionEvent.ACTION_POINTER_DOWN:
break;
case MotionEvent.ACTION_MOVE:
mCurStatus = MUTILMOVE;//双指
float X0 = event.getX(0);
float Y0 = event.getY(0);
float X1 = event.getX(1);
float Y1 = event.getY(1);
float k = (Y1 - Y0) / (X1 - X0);
float proportion = (Y0 * X1 - Y1 * X0) / (X1 - X0);
int RectCenterX = mZoomDrawableRect.centerX();
int RectCenterY = mZoomDrawableRect.centerY();
float mHandsX = (X0 + X1) / 2;
float mHandsY = mHandsX * k + proportion;
double mDoubleTwo = Math.sqrt(Math.pow(X0 - X1, 2)
+ Math.pow(Y0 - Y1, 2));
if (mDoubleOne < mDoubleTwo) {//放大
if (mZoomDrawableRect.width() < mContext.getResources()
.getDisplayMetrics().widthPixels * 2) {
int offsetwidth = 10;
int offsettop = (int) (offsetwidth / mRation_WH);
int l, r, t, b;
int left=mZoomDrawableRect.left;
int top = mZoomDrawableRect.top;
int right = mZoomDrawableRect.right;
int bottom = mZoomDrawableRect.bottom;
l=left-offsetwidth;
t=top-offsettop;
r = right + offsetwidth;
b = bottom + offsettop;
mZoomDrawableRect.set(l, t, r, b);
invalidate();
}
} else {//缩小
if (mZoomDrawableRect.width() > mContext.getResources()
.getDisplayMetrics().widthPixels / 3) {
int offsetwidth = 10;
int offsettop = (int) (offsetwidth / mRation_WH);
int l, r, t, b;
int left=mZoomDrawableRect.left;
int top = mZoomDrawableRect.top;
int right = mZoomDrawableRect.right;
int bottom = mZoomDrawableRect.bottom;
l=left+offsetwidth;
t=top+offsettop;
r = right - offsetwidth;
b = bottom - offsettop;
mZoomDrawableRect.set(l, t, r, b);
invalidate();
}
}
mDoubleOne = mDoubleTwo;
if (mHandsX < RectCenterX) {
if (mHandsY < RectCenterY) {
} else {
}
} else {
if (mHandsY < RectCenterY) {
} else {
}
}
break;
case MotionEvent.ACTION_UP:
mCurStatus = 0;
break;
default:
break;
}
break;
}
return true;
}
public void setBackground() {
if (isFirst) {
mRation_WH = (float) mZoomDrawable.getIntrinsicWidth()
/ (float) mZoomDrawable.getIntrinsicHeight();
int px_w = Math.min(getWidth(),
dip2px(mContext, mZoomDrawable.getIntrinsicWidth()));
int px_h = (int) (px_w / mRation_WH);
int left = (getWidth() - px_w) / 2;
int top = (getHeight() - px_h) / 2;
int right = px_w + left;
int bottom = px_h + top;
mZoomDrawableRect.set(left, top, right, bottom);
// mDrawableOffsetRect.set(mZoomDrawableRect);
isFirst = false;
}
mZoomDrawable.setBounds(mZoomDrawableRect);
}
public Drawable getmZoomDrawable() {
return mZoomDrawable;
}
public void setmZoomDrawable(Drawable mZoomDrawable) {
this.mZoomDrawable = mZoomDrawable;
}
public int dip2px(Context context, int value) {
final float scale = context.getResources().getDisplayMetrics().density;
return (int) (value * scale + 0.5f);
}
}
2.Activity中应用：
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.Window;
import com.xinrui.ndkapp.view.ZoomDragImageView;
public class ZoomActivity extends Activity {
Context mContext;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
this.mContext = getApplicationContext();
requestWindowFeature(Window.FEATURE_NO_TITLE);
ZoomDragImageView mView = new ZoomDragImageView(mContext);
mView.setmZoomDrawable(mContext.getResources().getDrawable(R.drawable.newpic));
setContentView(mView);
}
}