Добавлен Drawable для плавных переходов

src/com/annimon/everlastingsummer/drawables/TransitionAnimationDrawable.java

@@ -0,0 +1,144 @@
+package com.annimon.everlastingsummer.drawables;
+
+import java.util.ArrayList;
+import java.util.List;
+import android.graphics.Canvas;
+import android.graphics.drawable.ColorDrawable;
+import android.graphics.drawable.Drawable;
+import android.graphics.drawable.LayerDrawable;
+import android.os.SystemClock;
+
+/**
+ * Плавный переход между несколькими изображениями.
+ * @author aNNiMON
+ */
+public class TransitionAnimationDrawable extends LayerDrawable {
+    
+    private static final int TRANSITION_STARTING = 0;
+    private static final int TRANSITION_RUNNING = 1;
+    private static final int TRANSITION_NONE = 2;
+
+    private final int fullDuration;
+    private final int[] durations;
+    
+    private final int lastIndex;
+    private int state;
+    private long startTime;
+    private int currentDuration;
+    private int fromIndex, toIndex;
+
+    public TransitionAnimationDrawable(int fullDuration, int[] durations, Drawable[] drawables) {
+        super(drawables);
+        this.fullDuration = fullDuration;
+        this.durations = durations;
+        state = TRANSITION_NONE;
+        lastIndex = durations.length - 1;
+    }
+    
+    public int getFullDuration() {
+        return fullDuration;
+    }
+    
+    public void startTransition() {
+        fromIndex = 0;
+        toIndex = 1;
+        startTransitionAnimation();
+    }
+    
+    private void startTransitionAnimation() {
+        currentDuration = durations[toIndex];
+        state = TRANSITION_STARTING;
+        invalidateSelf();
+    }
+    
+    @Override
+    public void draw(Canvas canvas) {
+        boolean done = false;
+        int alpha = 0;
+        
+        switch (state) {
+            case TRANSITION_STARTING:
+                startTime = SystemClock.uptimeMillis();
+                state = TRANSITION_RUNNING;
+                break;
+                
+            case TRANSITION_RUNNING:
+                if (currentDuration <= 0) {
+                    done = true;
+                    alpha = 255;
+                    break;
+                }
+                float value = (SystemClock.uptimeMillis() - startTime) / (float) currentDuration;
+                if (value >= 1.0f) {
+                    done = true;
+                    value = 1.0f;
+                }
+                alpha = (int) (255 * value);
+                break;
+            default:
+                done = true;
+        }
+        
+        if (done) {
+//            getDrawable(fromIndex).draw(canvas);
+            getDrawable(toIndex).draw(canvas);
+            if (state == TRANSITION_RUNNING) {
+                if (toIndex < lastIndex) {
+                    // Новая итерация анимации
+                    fromIndex++;
+                    toIndex++;
+                    startTransitionAnimation();
+                } else {
+                    state = TRANSITION_NONE;
+                }
+            }
+            return;
+        }
+        
+        // Рисуем подкладку
+        Drawable d = getDrawable(fromIndex);
+        d.draw(canvas);
+        
+        // Рисуем наложенное изображение с прозрачностью
+        if (alpha > 0) {
+            d = getDrawable(toIndex);
+            d.setAlpha(alpha);
+            d.draw(canvas);
+        }
+        
+        if (!done) invalidateSelf();
+    }
+    
+    public static class Builder {
+        
+        private static final Drawable NONE = new ColorDrawable();
+        
+        private int fullDuration;
+        private final List<Integer> durations;
+        private final List<Drawable> drawables;
+        
+        public Builder() {
+            fullDuration = 0;
+            this.durations = new ArrayList<Integer>();
+            this.drawables = new ArrayList<Drawable>();
+        }
+        
+        public Builder add(int duration, Drawable drawable) {
+            fullDuration += duration;
+            durations.add(duration);
+            drawables.add(drawable == null ? NONE : drawable);
+            return this;
+        }
+        
+        public TransitionAnimationDrawable build() {
+            final int size = durations.size();
+            final int[] durationsArray = new int[size];
+            final Drawable[] drawablesArray = new Drawable[size];
+            for (int i = 0; i < size; i++) {
+                durationsArray[i] = durations.get(i);
+                drawablesArray[i] = drawables.get(i);
+            }
+            return new TransitionAnimationDrawable(fullDuration, durationsArray, drawablesArray);
+        }
+    }
+}