android imageView:设置拖动和捏缩放参数 [英] android imageView: setting drag and pinch zoom parameters

问题描述

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捏缩放和拖动.

I am currently developing for Android (my first app) an application which lets users see the subway map and be able to pinch zoom and drag around.

我目前正在修改 Hello Android，第 3 版中的代码，并让捏缩放和拖动工作.我使用 Matrix 作为我的布局比例.

I am currently modifying the code found in Hello Android, 3rd Edition and got the pinch zooming and dragging to work. I'm using Matrix as my layout scale.

但是我现在有 3 个问题:

However I now have 3 problems:

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(实际上可以从视图中消失).我尝试在 XML 文件中设置布局参数，但它不起作用.

1. I tried many things to limit the drag parameters but I can't seem to stop it being dragged off the parent view (and can actually disappear from view). I've tried setting layout parameters in the XML file and it just doesn't work.

我可以很好地捏缩放，但我又遇到了麻烦，限制缩放量.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)

I can pinch zoom fine but I have trouble, again, limiting the amount of zoom. I'm trying to play around with setting a max_zoom and min_zoom to limit the scaling value (i will post my code after)

我也很难在我的图像上绘制一个坐标，以便人们可以点击某些部分(这样做的重点是让用户点击地图上的一个站点并查看有关它的信息)

I also have trouble trying to map a coordinate on my image so that people can click on certain parts (the whole point of this is to let users click a station on the map and view information about it)

我觉得我遇到了麻烦，因为我使用的是矩阵刻度.

I have a feeling i'm having trouble because I'm using the matrix scale.

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，没什么复杂的):

<?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(只加了主题所以没有标题栏，全屏)

<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>

推荐答案

我刚刚创建了这个:

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

可能对某人有用...

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