记忆沉重的椭圆形渐变 [英] Memory heavy oval gradient
问题描述
您可能已经知道,无法使用常规Android API绘制椭圆形的径向渐变.
As you may know it is not possible to draw an oval radial gradient using regular Android API.
这是我想要实现的:
因此,我实现了此解决方案:在正方形位图上绘制规则的径向渐变,然后该位图将被视图本身拉伸(此处的想法是:https://stackoverflow.com/a/3543899/649910 )
So I implemented this solution: draw a regular radial gradient on a square bitmap and then this bitmap will get stretched by the view itself (idea found here: https://stackoverflow.com/a/3543899/649910)
这很好用,但是由于BitmapDrawable的使用,此解决方案需要大量内存(请参阅下面的实现详细信息).
This works great however this solution takes a lot of memory, because of BitmapDrawable usage (see implementation details below).
欢迎任何关于如何避免使用如此大的位图的想法!
Any ideas on how to avoid usage of such a big bitmap are welcome!
这是我的代码:
public class OvalGradientView extends ImageView {
private Drawable defaultBackgroundDrawable;
public OvalGradientView(Context context) {
super(context);
init();
}
public OvalGradientView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public OvalGradientView(Context context, AttributeSet attrs, int defStyleAttr, Paint paint) {
super(context, attrs, defStyleAttr);
init();
}
private void init() {
setScaleType(ScaleType.FIT_XY);
defaultBackgroundDrawable = getResources().getDrawable(R.drawable.default_background);
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
int width = getWidth();
int height = getHeight();
Rect currentBounds = defaultBackgroundDrawable.getBounds();
// check if we already have bitmap for these bounds
if (currentBounds.right == width && currentBounds.bottom == height) {
return;
}
// draw the drawable on square bitmap, it will be then stretched if needed to rectangular shape
// as the view gets more rectangular
defaultBackgroundDrawable.setBounds(0, 0, width, width);
Bitmap defaultBackgroundBitmap = Bitmap.createBitmap(width, width, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(defaultBackgroundBitmap);
defaultBackgroundDrawable.draw(canvas);
setImageBitmap(defaultBackgroundBitmap);
}
}
这是可绘制的XML-default_background
And this is the drawable XML - default_background
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<gradient
android:startColor="#ffffff"
android:endColor="#ff6600"
android:gradientRadius="50%p"
android:type="radial" />
</shape
推荐答案
我最终完成了此实现:
public class MyBackgroundView extends ImageView {
public MyBackgroundView(Context context) {
super(context);
}
public MyBackgroundView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public MyBackgroundView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
{
setBackgroundResource(R.drawable.my_background);
setScaleType(ScaleType.FIT_XY);
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
if (!changed) {
return;
}
int width = right - left;
int height = bottom - top;
float aspectRatio = (float) width / height;
if (aspectRatio > 1f) {
setScaleX(aspectRatio);
} else {
setScaleY(1 / aspectRatio);
}
}
}
其中my_background是:
where my_background is:
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<gradient
android:startColor="@color/my_background_start_color"
android:endColor="@color/my_background_end_color"
android:gradientRadius="@fraction/my_background_gradient_radius_percent"
android:type="radial" />
</shape>
此视图的宽度和高度均为match_parent.
Width and height of this view are both match_parent.
这篇关于记忆沉重的椭圆形渐变的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!