android imageView：设置拖动和捏缩放参数

Question

我目前正在为 Android（我的第一个应用程序）开发一个应用程序，它可以让用户查看地铁地图并能够进行缩放和拖动。

我目前正在修改 Hello Android，第 3 版中的代码，并让捏缩放和拖动功能正常工作。我使用 Matrix 作为布局比例。

然而我现在有 3 个问题：

1. 我尝试了很多方法来限制拖动参数，但我似乎无法阻止它被拖离父视图（并且实际上可以从视图中消失）。我已经尝试在 XML 文件中设置布局参数，但它不起作用。

2. 我可以很好地捏缩放，但我再次遇到限制缩放量的问题。我正在尝试设置 max_zoom 和 min_zoom 来限制缩放值（我将在之后发布我的代码）

3. 我在尝试在图像上映射坐标以便人们可以单击某些部分时也遇到了麻烦（这样做的全部目的是让用户单击地图上的一个站点并查看有关它的信息）

我感觉我遇到了麻烦，因为我正在使用矩阵比例。

这是我当前的代码：

Touch.java

package org.example.touch;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.os.Bundle;
import android.util.FloatMath;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.GridView;
import android.widget.ImageView;

public class Touch extends Activity implements OnTouchListener {
private static final String TAG = "Touch";

private static final float MIN_ZOOM = 1.0f;
private static final float MAX_ZOOM = 5.0f;

// These matrices will be used to move and zoom image
Matrix matrix = new Matrix();
Matrix savedMatrix = new Matrix();

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

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

@Override
public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.main);
   ImageView view = (ImageView) findViewById(R.id.imageView);
   //view.setLayoutParams(new GridView.LayoutParams(85, 85));
   view.setScaleType(ImageView.ScaleType.FIT_CENTER);
   view.setOnTouchListener(this);   
}

public boolean onTouch(View v, MotionEvent event) {
   ImageView view = (ImageView) v;
   view.setScaleType(ImageView.ScaleType.MATRIX);
   float scale;

   // Dump touch event to log
   dumpEvent(event);

   // Handle touch events here...
   switch (event.getAction() & MotionEvent.ACTION_MASK) {

   case MotionEvent.ACTION_DOWN: //first finger down only
      savedMatrix.set(matrix);
      start.set(event.getX(), event.getY());
      Log.d(TAG, "mode=DRAG" );
      mode = DRAG;
      break;
   case MotionEvent.ACTION_UP: //first finger lifted
   case MotionEvent.ACTION_POINTER_UP: //second finger lifted
      mode = NONE;
      Log.d(TAG, "mode=NONE" );
      break;
   case MotionEvent.ACTION_POINTER_DOWN: //second finger down
      oldDist = spacing(event);
      Log.d(TAG, "oldDist=" + oldDist);
      if (oldDist > 5f) {
         savedMatrix.set(matrix);
         midPoint(mid, event);
         mode = ZOOM;
         Log.d(TAG, "mode=ZOOM" );
      }
      break;

   case MotionEvent.ACTION_MOVE: 
      if (mode == DRAG) { //movement of first finger
         matrix.set(savedMatrix);
         if (view.getLeft() >= -392){
            matrix.postTranslate(event.getX() - start.x, event.getY() - start.y);
         }
      }
      else if (mode == ZOOM) { //pinch zooming
         float newDist = spacing(event);
         Log.d(TAG, "newDist=" + newDist);
         if (newDist > 5f) {
            matrix.set(savedMatrix);
            scale = newDist / oldDist; **//thinking i need to play around with this value to limit it**
            matrix.postScale(scale, scale, mid.x, mid.y);
         }
      }
      break;
   }

   // Perform the transformation
   view.setImageMatrix(matrix);

   return true; // indicate event was handled
}

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);
}

/** Show an event in the LogCat view, for debugging */
private void dumpEvent(MotionEvent event) {
   String names[] = { "DOWN" , "UP" , "MOVE" , "CANCEL" , "OUTSIDE" ,
      "POINTER_DOWN" , "POINTER_UP" , "7?" , "8?" , "9?" };
   StringBuilder sb = new StringBuilder();
   int action = event.getAction();
   int actionCode = action & MotionEvent.ACTION_MASK;
   sb.append("event ACTION_" ).append(names[actionCode]);
   if (actionCode == MotionEvent.ACTION_POINTER_DOWN
         || actionCode == MotionEvent.ACTION_POINTER_UP) {
      sb.append("(pid " ).append(
      action >> MotionEvent.ACTION_POINTER_ID_SHIFT);
      sb.append(")" );
   }
   sb.append("[" );
   for (int i = 0; i < event.getPointerCount(); i++) {
      sb.append("#" ).append(i);
      sb.append("(pid " ).append(event.getPointerId(i));
      sb.append(")=" ).append((int) event.getX(i));
      sb.append("," ).append((int) event.getY(i));
      if (i + 1 < event.getPointerCount())
         sb.append(";" );
   }
   sb.append("]" );
   Log.d(TAG, sb.toString());
}
}

ma​​in.xml （相当简单，没有什么真正复杂的）：

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent" >
<ImageView android:id="@+id/imageView"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent"
     android:src="@drawable/map"
     android:scaleType="matrix" >
</ImageView>
</FrameLayout>

AndroidManifest.xml （仅添加了主题，因此没有标题栏并且是全屏的）

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="org.example.touch"
  android:versionCode="7"
  android:versionName="1.0" >
<application android:icon="@drawable/icon" android:label="@string/app_name" android:theme="@android:style/Theme.NoTitleBar.Fullscreen" >
  <activity android:name=".Touch"
        android:label="@string/app_name" >
     <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
     </intent-filter>
  </activity>
</application>
<uses-sdk android:minSdkVersion="3" android:targetSdkVersion="7" />
</manifest>

Answer 1

我刚刚创建了这个：

https://github.com/jasonpolites/gesture-imageview

可能有用对于某人...

Answer 2

另一个可能对某些人有用的选择是使用 WebView，它内置了缩放控件。

WebView webView = new WebView(this);
webView.setBackgroundColor(0xff000000);
webView.setScrollBarStyle(WebView.SCROLLBARS_OUTSIDE_OVERLAY);
webView.getSettings().setBuiltInZoomControls(true);
webView.getSettings().setSupportZoom(true);
//webView.getSettings().setDisplayZoomControls(false);  // API 11
webView.loadDataWithBaseURL(null, getHtml(), "text/html", "UTF-8", null);
mainView.addView(webView, -1, -2);

Answer 3

我知道这已经很旧了，但我正在考虑这样做，并找到了一个效果很好的解决方案。在 switch 语句之后和设置矩阵之前，您可以像这样限制缩放：

private void limitZoom(Matrix m) {

    float[] values = new float[9];
    m.getValues(values);
    float scaleX = values[Matrix.MSCALE_X];
    float scaleY = values[Matrix.MSCALE_Y];
    if(scaleX > MAX_ZOOM) {
        scaleX = MAX_ZOOM;
    } else if(scaleX < MIN_ZOOM) {
        scaleX = MIN_ZOOM;
    }

    if(scaleY > MAX_ZOOM) {
        scaleY = MAX_ZOOM;
    } else if(scaleY < MIN_ZOOM) {
        scaleY = MIN_ZOOM;
    }

    values[Matrix.MSCALE_X] = scaleX;
    values[Matrix.MSCALE_Y] = scaleY; 
    m.setValues(values);
}

我仍在研究如何限制平移，但这应该适用于缩放限制。

编辑：这是限制翻译的解决方案。请注意，我这样做是为了全屏图像视图，这就是为什么我在限制因素中使用显示宽度和高度，但您也可以轻松地使用视图的宽度和高度。

private void limitDrag(Matrix m) {
    float[] values = new float[9];
    m.getValues(values);
    float transX = values[Matrix.MTRANS_X];
    float transY = values[Matrix.MTRANS_Y];
    float scaleX = values[Matrix.MSCALE_X];
    float scaleY = values[Matrix.MSCALE_Y];

    ImageView iv = (ImageView)findViewById(R.id.photo_view);
    Rect bounds = iv.getDrawable().getBounds();
    int viewWidth = getResources().getDisplayMetrics().widthPixels;
    int viewHeight = getResources().getDisplayMetrics().heightPixels;

    int width = bounds.right - bounds.left;
    int height = bounds.bottom - bounds.top;

    float minX = (-width + 20) * scaleX; 
    float minY = (-height + 20) * scaleY;

    if(transX > (viewWidth - 20)) {
        transX = viewWidth - 20;
    } else if(transX < minX) {
        transX = minX;
    }

    if(transY > (viewHeight - 80)) {
        transY = viewHeight - 80;
    } else if(transY < minY) {
        transY = minY;
    }

    values[Matrix.MTRANS_X] = transX;
    values[Matrix.MTRANS_Y] = transY; 
    m.setValues(values);
}

再次强调，这将在 switch 语句之后、在视图中设置图像矩阵之前进行。我也将缩放限制分解为一个函数，它反映在上面。

Answer 4

下载源代码。
因此，您还可以获得 a) 点击、b) 拖动和 c) 捏缩放。
http://pragprog.com/titles/eband3/source_code

Answer 5

这是捏拉缩放和平移的完整代码（Touch.java，做了一些修改，可以实际使用）

public class Touch implements OnTouchListener {  

 // These matrices will be used to move and zoom image  
public static Matrix matrix = new Matrix();  
public static Matrix savedMatrix = new Matrix();  

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

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

 int width,height;

 @Override  
 public boolean onTouch(View v, MotionEvent event) {


  ImageView view = (ImageView) v;
  Rect bounds = view.getDrawable().getBounds();

  width = bounds.right - bounds.left;
  height = bounds.bottom - bounds.top;
  // Dump touch event to log  
  dumpEvent(event);  

  // 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;  
   break;  
  case MotionEvent.ACTION_POINTER_DOWN:  
   oldDist = spacing(event);  
   if (oldDist > 10f) {  
    savedMatrix.set(matrix);  
    midPoint(mid, event);  
    mode = ZOOM;  
   }  
   break;  
  case MotionEvent.ACTION_UP:  
  case MotionEvent.ACTION_POINTER_UP:  
   mode = NONE;  
   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) {  
    float newDist = spacing(event);  
    if (newDist > 10f) {  
     matrix.set(savedMatrix);  
     float scale = newDist / oldDist;  
     matrix.postScale(scale, scale, mid.x, mid.y);  
    }  
   }  
   break;  
  }  
//----------------------------------------------------
  limitZoom(matrix);
  limitDrag( matrix);
//----------------------------------------------------  
  view.setImageMatrix(matrix);  
  return true; // indicate event was handled  
 }  

 /** Show an event in the LogCat view, for debugging */  
 private void dumpEvent(MotionEvent event) {  
  String names[] = { "DOWN", "UP", "MOVE", "CANCEL", "OUTSIDE",  
    "POINTER_DOWN", "POINTER_UP", "7?", "8?", "9?" };  
  StringBuilder sb = new StringBuilder();  
  int action = event.getAction();  
  int actionCode = action & MotionEvent.ACTION_MASK;  
  sb.append("event ACTION_").append(names[actionCode]);  
  if (actionCode == MotionEvent.ACTION_POINTER_DOWN  
    || actionCode == MotionEvent.ACTION_POINTER_UP) {  
   sb.append("(pid ").append(  
     action >> MotionEvent.ACTION_POINTER_ID_SHIFT);  
   sb.append(")");  
  }  
  sb.append("[");  
  for (int i = 0; i < event.getPointerCount(); i++) {  
   sb.append("#").append(i);  
   sb.append("(pid ").append(event.getPointerId(i));  
   sb.append(")=").append((int) event.getX(i));  
   sb.append(",").append((int) event.getY(i));  
   if (i + 1 < event.getPointerCount())  
    sb.append(";");  
  }  
  sb.append("]");  
 }  

 /** Determine the space between the first two fingers */  
 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);  
 }  

 /** Calculate the mid point of the first two fingers */  
 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);  
 }  

 private void limitZoom(Matrix m) {

        float[] values = new float[9];
        m.getValues(values);
        float scaleX = values[Matrix.MSCALE_X];
        float scaleY = values[Matrix.MSCALE_Y];
        if(scaleX > MAX_ZOOM) {
            scaleX = MAX_ZOOM;
        } else if(scaleX < MIN_ZOOM) {
            scaleX = MIN_ZOOM;
        }

        if(scaleY > MAX_ZOOM) {
            scaleY = MAX_ZOOM;
        } else if(scaleY < MIN_ZOOM) {
            scaleY = MIN_ZOOM;
        }

        values[Matrix.MSCALE_X] = scaleX;
        values[Matrix.MSCALE_Y] = scaleY; 
        m.setValues(values);
    }


 private void limitDrag(Matrix m) {

        float[] values = new float[9];
        m.getValues(values);
        float transX = values[Matrix.MTRANS_X];
        float transY = values[Matrix.MTRANS_Y];
        float scaleX = values[Matrix.MSCALE_X];
        float scaleY = values[Matrix.MSCALE_Y];
//--- limit moving to left ---
        float minX = (-width + 0) * (scaleX-1); 
        float minY = (-height + 0) * (scaleY-1);
//--- limit moving to right ---     
        float maxX=minX+width*(scaleX-1);
        float maxY=minY+height*(scaleY-1);
        if(transX>maxX){transX = maxX;}
        if(transX<minX){transX = minX;}
        if(transY>maxY){transY = maxY;}
        if(transY<minY){transY = minY;}
        values[Matrix.MTRANS_X] = transX;
        values[Matrix.MTRANS_Y] = transY; 
        m.setValues(values);
    }

}

Answer 6

使用以下链接中 Phyxdevel 评论中的代码
ZDNET 缩放示例。

他有限制平移和缩放级别的代码。

Answer 7

您可以使用以下代码来限制底部和右侧

float maxX = minX+viewWidth; 
int offsetY = 80;
        float maxY = minY+viewHeight-offsetY;
       if(x>maxX){
           mPosX = maxX;
       }
       if(x<minX){
           mPosX = minX;
       }
       if(y>maxY){
           mPosY = maxY;
       }
       if(y<minY){
           mPosY = minY;
       }