带矢量绘图的TransitionDrawable

Question

我在xml中定义了TransitionDrawable，如下所示：

transition.xml

<?xml version="1.0" encoding="utf-8"?>
<transition xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/ic_disabled" />
    <item android:drawable="@drawable/ic_enabled" />
</transition>

我使用它来激活状态更改复选框：

val stateDrawable = ContextCompat.getDrawable(this, R.drawable.transition) as TransitionDrawable
checkbox.buttonDrawable = stateDrawable
checkbox.setOnCheckedChangeListener { icon, checked -> 
    if (checked) {
        stateDrawable.startTransition(300) 
    } else {
        stateDrawable.reverseTransition(300)
    }
}

如果@drawable/ic_disabled和@drawable/ic_enabled是png文件，那么一切都正常。但是，如果它们是向量可绘制的，则转换不起作用。我遗漏了什么？TransitionDrawable不支持矢量绘图吗？

Answer 1

我知道这很古老，但我也有同样的问题.在添加到BitmapDrawable之前，必须将向量转换为TransitionDrawable。下面是一个例子

            TransitionDrawable td = new TransitionDrawable(new Drawable[]{
                    getBitmapDrawableFromVectorDrawable(this, R.drawable.vector1),
                    getBitmapDrawableFromVectorDrawable(this, R.drawable.vector2)
            });
            td.setCrossFadeEnabled(true); // probably want this

            // set as checkbox button drawable...

实用程序方法//见https://stackoverflow.com/a/38244327/114549

public static BitmapDrawable getBitmapDrawableFromVectorDrawable(Context context, int drawableId) {
    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
        return (BitmapDrawable) ContextCompat.getDrawable(context, drawableId);
    }
    return new BitmapDrawable(context.getResources(), getBitmapFromVectorDrawable(context, drawableId));
}

public static Bitmap getBitmapFromVectorDrawable(Context context, int drawableId) {
    Drawable drawable = ContextCompat.getDrawable(context, drawableId);
    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
        drawable = (DrawableCompat.wrap(drawable)).mutate();
    }

    Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(),
            drawable.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);
    drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
    drawable.draw(canvas);

    return bitmap;
}

Answer 2

因为我所想要的只是用淡色来改变图像，所以我实现了一个简单的TransitionDrawable版本，它似乎适用于固定大小的矢量绘图。

public class SimpleTransitionDrawable extends Drawable {
    private static final int TRANSITION_STARTING = 0;
    private static final int TRANSITION_RUNNING = 1;
    private static final int TRANSITION_NONE = 2;

    private int state = TRANSITION_NONE;

    private long startTimeMillis;
    private int duration;

    private @Nullable Drawable source;
    private Drawable target;

    public void setTarget(Drawable target) {
        this.source = this.target;
        this.target = target;
        target.setBounds(0, 0, target.getIntrinsicWidth(), target.getIntrinsicHeight());
    }

    public void startTransition(int durationMillis) {
        duration = durationMillis;
        state = TRANSITION_STARTING;
        invalidateSelf();
    }

    @Override
    public void draw(Canvas canvas) {
        int alpha;

        switch (state) {
            case TRANSITION_STARTING:
                startTimeMillis = SystemClock.uptimeMillis();
                alpha = 0;
                state = TRANSITION_RUNNING;
                break;

            case TRANSITION_RUNNING:
                float normalized = (float) (SystemClock.uptimeMillis() - startTimeMillis) / duration;
                alpha = (int) (0xff * Math.min(normalized, 1.0f));
                break;

            default:
                if (target == null) return;
                alpha = 0xff;
                break;
        }

        if (source != null && alpha < 0xff) {
            source.setAlpha(0xff - alpha);
            source.draw(canvas);
        }

        if (alpha > 0) {
            target.setAlpha(alpha);
            target.draw(canvas);
        }

        if (alpha == 0xff) {
            state = TRANSITION_NONE;
            return;
        }

        invalidateSelf();
    }

    @Override public void setAlpha(int alpha) {}

    @Override public void setColorFilter(ColorFilter colorFilter) {}

    @Override public int getOpacity() {return PixelFormat.TRANSLUCENT;}
}

将其初始化如下：

ImageView view = findViewById(R.id.image_view);
SimpleTransitionDrawable drawable = new SimpleTransitionDrawable();
view.setImageDrawable(drawable);

然后用淡色修改可绘制的：

drawable.setTarget(AppCompatResources.getDrawable(this, R.drawable.my_vector));
drawable.startTransition(350);

Answer 3

遵循@aaronvargas https://stackoverflow.com/a/54583929/1508956的相同方法

我创建了一些扩展函数，它封装了实现并使可用性更容易

fun Drawable.getBitmapDrawableFromVectorDrawable(context: Context): BitmapDrawable {
    return BitmapDrawable(context.resources, getBitmapFromVectorDrawable())
}

fun Drawable.getBitmapFromVectorDrawable(): Bitmap {
    val bitmap = Bitmap.createBitmap(
        intrinsicWidth,
        intrinsicHeight, Bitmap.Config.ARGB_8888
    )

    val canvas = Canvas(bitmap)
    setBounds(0, 0, canvas.width, canvas.height)
    draw(canvas)

    return bitmap
}

fun ImageView.setTransitionDrawable(vectorID: Int, firstColor: Int, secondColor: Int): TransitionDrawable? {
    val drawables = arrayOfNulls<Drawable>(2)

    val firstDrawable = ContextCompat.getDrawable(context, vectorID) ?: return null
    DrawableCompat.setTint(firstDrawable, ContextCompat.getColor(context, firstColor))
    drawables[0] = firstDrawable.getBitmapDrawableFromVectorDrawable(context)

    val secondDrawable = ContextCompat.getDrawable(context, vectorID) ?: return null
    DrawableCompat.setTint(secondDrawable, ContextCompat.getColor(context, secondColor))
    drawables[1] = secondDrawable.getBitmapDrawableFromVectorDrawable(context)

    val transition = TransitionDrawable(drawables)
    transition.isCrossFadeEnabled = true
    setImageDrawable(transition)

    return transition
}

初始化：

val transition = imageView.setTransitionDrawable(resourceID, R.color.firstColor, R.color.secondColor)
transition?.startTransition(3000)