Added random scene generator

Author: tsuijten

library/src/main/java/com/q42/android/scrollingimageview/ScrollingImageView.java

@@ -7,17 +7,22 @@
 import android.graphics.Canvas;
 import android.graphics.Rect;
 import android.util.AttributeSet;
+import android.util.TypedValue;
 import android.view.View;
 
+import java.util.Random;
+
 import static java.lang.Math.abs;
-import static java.lang.Math.floor;
 
 /**
  * Created by thijs on 08-06-15.
  */
 public class ScrollingImageView extends View {
-    private final int speed;
-    private final Bitmap bitmap;
+    private Bitmap[] bitmaps;
+    private float speed;
+    private int[] scene;
+    private int arrayIndex = 0;
+    private int maxBitmapHeight = 0;
 
     private Rect clipBounds = new Rect();
     private float offset = 0;
@@ -28,8 +33,32 @@ public ScrollingImageView(Context context, AttributeSet attrs) {
         super(context, attrs);
         TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.ParallaxView, 0, 0);
         try {
-            speed = ta.getDimensionPixelSize(R.styleable.ParallaxView_speed, 10);
-            bitmap = BitmapFactory.decodeResource(getResources(), ta.getResourceId(R.styleable.ParallaxView_src, 0));
+            speed = ta.getDimension(R.styleable.ParallaxView_speed, 10);
+            int sceneLength = ta.getInt(R.styleable.ParallaxView_sceneLength, 1000);
+            int type = ta.peekValue(R.styleable.ParallaxView_src).type;
+            if (type == TypedValue.TYPE_REFERENCE) {
+                int resourceId = ta.getResourceId(R.styleable.ParallaxView_src, 0);
+                TypedArray typedArray = getResources().obtainTypedArray(resourceId);
+                try {
+                    bitmaps = new Bitmap[typedArray.length()];
+                    for (int i = 0; i < typedArray.length(); i++) {
+                        bitmaps[i] = BitmapFactory.decodeResource(getResources(), typedArray.getResourceId(i, 0));
+                        maxBitmapHeight = Math.max(bitmaps[i].getHeight(), maxBitmapHeight);
+                    }
+
+                    Random random = new Random();
+                    this.scene = new int[sceneLength];
+                    for (int i = 0; i < this.scene.length; i++) {
+                        this.scene[i] = random.nextInt(bitmaps.length);
+                    }
+                } finally {
+                    typedArray.recycle();
+                }
+            } else if (type == TypedValue.TYPE_STRING) {
+                bitmaps = new Bitmap[]{BitmapFactory.decodeResource(getResources(), ta.getResourceId(R.styleable.ParallaxView_src, 0))};
+                scene = new int[]{0};
+                maxBitmapHeight = bitmaps[0].getHeight();
+            }
         } finally {
             ta.recycle();
         }
@@ -39,7 +68,7 @@ public ScrollingImageView(Context context, AttributeSet attrs) {
     @Override
     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
         super.onMeasure(widthMeasureSpec, heightMeasureSpec);
-        setMeasuredDimension(MeasureSpec.getSize(widthMeasureSpec), bitmap.getHeight());
+        setMeasuredDimension(MeasureSpec.getSize(widthMeasureSpec), maxBitmapHeight);
     }
 
     @Override
@@ -51,15 +80,17 @@ public void onDraw(Canvas canvas) {
 
         canvas.getClipBounds(clipBounds);
 
-        float layerWidth = bitmap.getWidth();
-        if (offset < -layerWidth) {
-            offset += (floor(abs(offset) / layerWidth) * layerWidth);
+        while (offset <= -getBitmap(arrayIndex).getWidth()) {
+            offset += getBitmap(arrayIndex).getWidth();
+            arrayIndex = (arrayIndex + 1) % scene.length;
         }
 
         float left = offset;
-        while (left < clipBounds.width()) {
-            canvas.drawBitmap(bitmap, getBitmapLeft(layerWidth, left), 0, null);
-            left += layerWidth;
+        for (int i = 0; left < clipBounds.width(); i++) {
+            Bitmap bitmap = getBitmap((arrayIndex + i) % scene.length);
+            int width = bitmap.getWidth();
+            canvas.drawBitmap(bitmap, getBitmapLeft(width, left), 0, null);
+            left += width;
         }
 
         if (isStarted) {
@@ -68,6 +99,10 @@ public void onDraw(Canvas canvas) {
         }
     }
 
+    private Bitmap getBitmap(int sceneIndex) {
+        return bitmaps[scene[sceneIndex]];
+    }
+
     private float getBitmapLeft(float layerWidth, float left) {
         if (speed < 0) {
             return clipBounds.width() - layerWidth - left;

library/src/main/res/values/attr.xml

@@ -3,5 +3,6 @@
     <declare-styleable name="ParallaxView">
         <attr name="speed" format="dimension" />
         <attr name="src" format="reference" />
+        <attr name="sceneLength" format="integer" />
     </declare-styleable>
 </resources>

sampleapp/src/main/AndroidManifest.xml

@@ -9,7 +9,7 @@
         android:theme="@style/AppTheme" >
         <activity
             android:name=".MainActivity"
-            android:label="@string/app_name" >
+            android:label="@string/app_name">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
 

sampleapp/src/main/res/layout/activity_main.xml

@@ -26,6 +26,7 @@
             android:layout_marginTop="10dp">
 
             <com.q42.android.scrollingimageview.ScrollingImageView
+                android:id="@+id/thijs"
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"
                 android:layout_gravity="bottom"

sampleapp/src/main/res/values/arrays.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <array name="random_imgs">
+        <item>@drawable/van</item>
+        <item>@drawable/layer_7</item>
+    </array>
+</resources>