15 ScalableImageView

15_scalableimageview/.gitignore

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+/build

15_scalableimageview/build.gradle

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+apply plugin: 'com.android.application'
+
+android {
+    compileSdkVersion 28
+
+
+
+    defaultConfig {
+        applicationId "com.hencoder.a15_scalableimageview"
+        minSdkVersion 21
+        targetSdkVersion 28
+        versionCode 1
+        versionName "1.0"
+
+        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
+
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+
+}
+
+dependencies {
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+
+    implementation 'com.android.support:appcompat-v7:28.0.0'
+    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
+    testImplementation 'junit:junit:4.12'
+    androidTestImplementation 'com.android.support.test:runner:1.0.2'
+    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
+}

15_scalableimageview/proguard-rules.pro

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+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

15_scalableimageview/src/androidTest/java/com/hencoder/a15_scalableimageview/ExampleInstrumentedTest.java

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+package com.hencoder.a15_scalableimageview;
+
+import android.content.Context;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.runner.AndroidJUnit4;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import static org.junit.Assert.*;
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * @see <a href="http://d.android.com/tools/testing">Testing documentation</a>
+ */
+@RunWith(AndroidJUnit4.class)
+public class ExampleInstrumentedTest {
+    @Test
+    public void useAppContext() {
+        // Context of the app under test.
+        Context appContext = InstrumentationRegistry.getTargetContext();
+
+        assertEquals("com.hencoder.scalableimageview", appContext.getPackageName());
+    }
+}

15_scalableimageview/src/main/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.hencoder.a15_scalableimageview">
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/AppTheme">
+        <activity android:name="com.hencoder.a15_scalableimageview.MainActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>

15_scalableimageview/src/main/java/com/hencoder/a15_scalableimageview/MainActivity.java

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+package com.hencoder.a15_scalableimageview;
+
+import android.os.Bundle;
+
+import androidx.appcompat.app.AppCompatActivity;
+
+public class MainActivity extends AppCompatActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_main);
+    }
+}

15_scalableimageview/src/main/java/com/hencoder/a15_scalableimageview/Utils.java

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+package com.hencoder.a15_scalableimageview;
+
+import android.content.res.Resources;
+import android.graphics.Bitmap;
+import android.graphics.BitmapFactory;
+import android.util.TypedValue;
+
+public class Utils {
+    public static float dpToPixel(float dp) {
+        return  TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp,
+                Resources.getSystem().getDisplayMetrics());
+    }
+
+    public static Bitmap getAvatar(Resources res, int width) {
+        BitmapFactory.Options options = new BitmapFactory.Options();
+        options.inJustDecodeBounds = true;
+        BitmapFactory.decodeResource(res, R.drawable.avatar_rengwuxian, options);
+        options.inJustDecodeBounds = false;
+        options.inDensity = options.outWidth;
+        options.inTargetDensity = width;
+        return BitmapFactory.decodeResource(res, R.drawable.avatar_rengwuxian, options);
+    }
+}

15_scalableimageview/src/main/java/com/hencoder/a15_scalableimageview/view/ScalableImageView.java

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+package com.hencoder.a15_scalableimageview.view;
+
+import android.animation.ObjectAnimator;
+import android.content.Context;
+import android.graphics.Bitmap;
+import android.graphics.Canvas;
+import android.graphics.Paint;
+import android.util.AttributeSet;
+import android.view.GestureDetector;
+import android.view.MotionEvent;
+import android.view.View;
+import android.widget.OverScroller;
+
+import com.hencoder.a15_scalableimageview.Utils;
+
+import androidx.annotation.Nullable;
+import androidx.core.view.GestureDetectorCompat;
+import androidx.core.view.ViewCompat;
+
+public class ScalableImageView extends View implements GestureDetector.OnGestureListener, GestureDetector.OnDoubleTapListener, Runnable {
+    private static final float IMAGE_WIDTH = Utils.dpToPixel(300);
+    private static final float OVER_SCALE_FACTOR = 1.5f;
+
+    Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
+    Bitmap bitmap;
+    float originalOffsetX;
+    float originalOffsetY;
+    float offsetX;
+    float offsetY;
+    float smallScale;
+    float bigScale;
+    boolean big;
+    float scaleFraction;
+    ObjectAnimator scaleAnimator;
+    OverScroller scroller;
+
+    GestureDetectorCompat detector;
+
+    public ScalableImageView(Context context, @Nullable AttributeSet attrs) {
+        super(context, attrs);
+
+        bitmap = Utils.getAvatar(getResources(), (int) IMAGE_WIDTH);
+        detector = new GestureDetectorCompat(context, this);
+        scroller = new OverScroller(context);
+    }
+
+    public float getScaleFraction() {
+        return scaleFraction;
+    }
+
+    public void setScaleFraction(float scaleFraction) {
+        this.scaleFraction = scaleFraction;
+        invalidate();
+    }
+
+    private ObjectAnimator getScaleAnimator() {
+        if (scaleAnimator == null) {
+            scaleAnimator = ObjectAnimator.ofFloat(this, "scaleFraction", 0, 1);
+        }
+        return scaleAnimator;
+    }
+
+    @Override
+    public boolean onTouchEvent(MotionEvent event) {
+        return detector.onTouchEvent(event);
+    }
+
+    @Override
+    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
+        super.onSizeChanged(w, h, oldw, oldh);
+
+        originalOffsetX = (getWidth() - bitmap.getWidth()) / 2f;
+        originalOffsetY = (getHeight() - bitmap.getHeight()) / 2f;
+
+        if ((float) bitmap.getWidth() / bitmap.getHeight() > (float) getWidth() / getHeight()) {
+            smallScale = (float) getWidth() / bitmap.getWidth();
+            bigScale = (float) getHeight() / bitmap.getHeight() * OVER_SCALE_FACTOR;
+        } else {
+            smallScale = (float) getHeight() / bitmap.getHeight();
+            bigScale = (float) getWidth() / bitmap.getWidth() * OVER_SCALE_FACTOR;
+        }
+    }
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+        super.onDraw(canvas);
+
+        canvas.translate(offsetX * scaleFraction, offsetY * scaleFraction);
+        float scale = smallScale + (bigScale - smallScale) * scaleFraction;
+        canvas.scale(scale, scale, getWidth() / 2f, getHeight() / 2f);
+        canvas.drawBitmap(bitmap, originalOffsetX, originalOffsetY, paint);
+    }
+
+    @Override
+    public boolean onDown(MotionEvent e) {
+        return true;
+    }
+
+    @Override
+    public void onShowPress(MotionEvent e) {
+
+    }
+
+    @Override
+    public boolean onSingleTapUp(MotionEvent e) {
+        return false;
+    }
+
+    @Override
+    public boolean onScroll(MotionEvent downEvent, MotionEvent event, float distanceX, float distanceY) {
+        if (big) {
+            offsetX -= distanceX;
+            offsetY -= distanceY;
+            fixOffsets();
+            invalidate();
+        }
+        return false;
+    }
+
+    @Override
+    public void onLongPress(MotionEvent e) {
+
+    }
+
+    @Override
+    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
+        if (big) {
+            scroller.fling((int) offsetX, (int) offsetY, (int) velocityX, (int) velocityY,
+                    - (int) ((bitmap.getWidth() * bigScale - getWidth()) / 2),
+                    (int) ((bitmap.getWidth() * bigScale - getWidth()) / 2),
+                    - (int) ((bitmap.getHeight() * bigScale - getHeight()) / 2),
+                    (int) ((bitmap.getHeight() * bigScale - getHeight()) / 2));
+
+            postOnAnimation(this);
+        }
+        return false;
+    }
+
+    @Override
+    public boolean onSingleTapConfirmed(MotionEvent e) {
+        return false;
+    }
+
+    @Override
+    public boolean onDoubleTap(MotionEvent e) {
+        big = !big;
+        if (big) {
+            offsetX = (e.getX() - getWidth() / 2f) * (1 - bigScale / smallScale);
+            offsetY = (e.getY() - getHeight() / 2f) * (1 - bigScale / smallScale);
+            fixOffsets();
+            getScaleAnimator().start();
+        } else {
+            getScaleAnimator().reverse();
+        }
+        return false;
+    }
+
+    private void fixOffsets() {
+        offsetX = Math.min(offsetX, (bitmap.getWidth() * bigScale - getWidth()) / 2);
+        offsetX = Math.max(offsetX, - (bitmap.getWidth() * bigScale - getWidth()) / 2);
+        offsetY = Math.min(offsetY, (bitmap.getHeight() * bigScale - getHeight()) / 2);
+        offsetY = Math.max(offsetY, - (bitmap.getHeight() * bigScale - getHeight()) / 2);
+    }
+
+    @Override
+    public boolean onDoubleTapEvent(MotionEvent e) {
+        return false;
+    }
+
+    @Override
+    public void run() {
+        if (scroller.computeScrollOffset()) {
+            offsetX = scroller.getCurrX();
+            offsetY = scroller.getCurrY();
+            invalidate();
+            postOnAnimation(this);
+        }
+    }
+}

15_scalableimageview/src/main/res/drawable-v24/ic_launcher_foreground.xml

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+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:aapt="http://schemas.android.com/aapt"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path
+        android:fillType="evenOdd"
+        android:pathData="M32,64C32,64 38.39,52.99 44.13,50.95C51.37,48.37 70.14,49.57 70.14,49.57L108.26,87.69L108,109.01L75.97,107.97L32,64Z"
+        android:strokeWidth="1"
+        android:strokeColor="#00000000">
+        <aapt:attr name="android:fillColor">
+            <gradient
+                android:endX="78.5885"
+                android:endY="90.9159"
+                android:startX="48.7653"
+                android:startY="61.0927"
+                android:type="linear">
+                <item
+                    android:color="#44000000"
+                    android:offset="0.0" />
+                <item
+                    android:color="#00000000"
+                    android:offset="1.0" />
+            </gradient>
+        </aapt:attr>
+    </path>
+    <path
+        android:fillColor="#FFFFFF"
+        android:fillType="nonZero"
+        android:pathData="M66.94,46.02L66.94,46.02C72.44,50.07 76,56.61 76,64L32,64C32,56.61 35.56,50.11 40.98,46.06L36.18,41.19C35.45,40.45 35.45,39.3 36.18,38.56C36.91,37.81 38.05,37.81 38.78,38.56L44.25,44.05C47.18,42.57 50.48,41.71 54,41.71C57.48,41.71 60.78,42.57 63.68,44.05L69.11,38.56C69.84,37.81 70.98,37.81 71.71,38.56C72.44,39.3 72.44,40.45 71.71,41.19L66.94,46.02ZM62.94,56.92C64.08,56.92 65,56.01 65,54.88C65,53.76 64.08,52.85 62.94,52.85C61.8,52.85 60.88,53.76 60.88,54.88C60.88,56.01 61.8,56.92 62.94,56.92ZM45.06,56.92C46.2,56.92 47.13,56.01 47.13,54.88C47.13,53.76 46.2,52.85 45.06,52.85C43.92,52.85 43,53.76 43,54.88C43,56.01 43.92,56.92 45.06,56.92Z"
+        android:strokeWidth="1"
+        android:strokeColor="#00000000" />
+</vector>