Android Shape Drawable 更改属性
Android Shape Drawable changing attributes
我有几个形状可绘制资源,我想将它们用作按钮的背景,除了渐变开始和结束颜色以及描边颜色外,它们很相似。
问题是我不想为此可绘制对象创建几个类似的 XML 文件。
我想我可以像使用标签的样式一样继承可绘制的形状,但这是不可能的。
我找到了这个 Defining XML Parent Style of Gradient / Shape / Corners 但我不明白它是如何工作的。他如何更改属性值?
那里 Using parents for drawable resources 我发现我可以通过图层列表更改背景的外观,图层列表将一层一层地绘制可绘制对象。但是如何使用图层列表来处理渐变和笔触颜色?
我发现我可以在运行时更改按钮背景的外观,但可能有更简单的方法来做到这一点?
我最初的建议是不可行的。我以为 <shape>
会 return 变成 ShapeDrawable
但我错了,下面是我将如何修改渐变。
点击按钮之前
点击按钮后,背景发生变化。
这是主要的Activity
public class MainActivity extends Activity {
Button button;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = (Button)findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
try
{
// you can use the GradientDrawable directly, check the docs for details,
// I extended GradientDrawable just to make myself look like a badass :)
MyReflection.invokeMethod(button, new Gradient(), "setBackground");
}
catch (NoSuchMethodException e)
{
e.printStackTrace();
}
catch (InvocationTargetException e)
{
e.printStackTrace();
}
catch (IllegalAccessException e)
{
e.printStackTrace();
}
}
});
}
}
获取新方法的实用程序方法,其中包含调用方法的对象、用作新背景的 Drawable
以及不带 ()
的方法名称,例如setBackground
到 运行 旧版本。反射很慢。谨慎使用。
/*
* We want to use reflection because the View.setBackground() method
* is only available on API level 16 and up.
* If you don't understand this, you can follow the tutorial provided by
* Oracle, just search for it on Google with the keyword "reflection tutorial"
*/
public class MyReflection {
public static void invokeMethod(Object receiverObject, Drawable background, String methodName)
throws NoSuchMethodException, InvocationTargetException, IllegalAccessException
{
Class<?> clazz = View.class;
Method method = clazz.getMethod(methodName, Drawable.class);
// Allowing non-public access call to this method.
method.setAccessible(true);
method.invoke(receiverObject, background);
}
}
我的自定义渐变
/**
* I am extending the GradientDrawable just for fun, and also
* because I want to set the shader property for this drawable,
* you could, however, use the GradientDrawable directly.
*/
public class Gradient extends GradientDrawable {
private Paint paint;
private LinearGradient gradient;
public Gradient()
{
super();
// check the docs for LinearGradient for these parameters
gradient = new LinearGradient(0,0, 100, 100, Color.BLUE, Color.GREEN, Shader.TileMode.REPEAT);
paint = new Paint();
paint.setShader(gradient);
}
public Gradient(GradientDrawable.Orientation orientation, int[] colors)
{
super(orientation, colors);
gradient = new LinearGradient(0,0, 100, 100, Color.BLUE, Color.GREEN, Shader.TileMode.REPEAT);
paint = new Paint();
paint.setShader(gradient);
}
@Override
public void draw(Canvas canvas)
{
canvas.drawPaint(paint);
}
}
按钮的初始背景
<?xml version="1.0" encoding="utf-8"?>
<!-- The initial shape with just a solid yellow color -->
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<solid
android:color="#ff0"/>
</shape>
哈,我没有使用 Reflections,而是根据当前版本使用这段代码来设置适当的背景
int sdk = android.os.Built.VERSION.SDK_INT;
if(sdk < android.os.Build.VERSION_CODES.JELLY_BEAN) {
setBackgroundDrawable();
} else {
setBackground();
}
我有几个形状可绘制资源,我想将它们用作按钮的背景,除了渐变开始和结束颜色以及描边颜色外,它们很相似。 问题是我不想为此可绘制对象创建几个类似的 XML 文件。
我想我可以像使用标签的样式一样继承可绘制的形状,但这是不可能的。
我找到了这个 Defining XML Parent Style of Gradient / Shape / Corners 但我不明白它是如何工作的。他如何更改属性值?
那里 Using parents for drawable resources 我发现我可以通过图层列表更改背景的外观,图层列表将一层一层地绘制可绘制对象。但是如何使用图层列表来处理渐变和笔触颜色?
我发现我可以在运行时更改按钮背景的外观,但可能有更简单的方法来做到这一点?
我最初的建议是不可行的。我以为 <shape>
会 return 变成 ShapeDrawable
但我错了,下面是我将如何修改渐变。
点击按钮之前
点击按钮后,背景发生变化。
这是主要的Activity
public class MainActivity extends Activity {
Button button;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = (Button)findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
try
{
// you can use the GradientDrawable directly, check the docs for details,
// I extended GradientDrawable just to make myself look like a badass :)
MyReflection.invokeMethod(button, new Gradient(), "setBackground");
}
catch (NoSuchMethodException e)
{
e.printStackTrace();
}
catch (InvocationTargetException e)
{
e.printStackTrace();
}
catch (IllegalAccessException e)
{
e.printStackTrace();
}
}
});
}
}
获取新方法的实用程序方法,其中包含调用方法的对象、用作新背景的 Drawable
以及不带 ()
的方法名称,例如setBackground
到 运行 旧版本。反射很慢。谨慎使用。
/*
* We want to use reflection because the View.setBackground() method
* is only available on API level 16 and up.
* If you don't understand this, you can follow the tutorial provided by
* Oracle, just search for it on Google with the keyword "reflection tutorial"
*/
public class MyReflection {
public static void invokeMethod(Object receiverObject, Drawable background, String methodName)
throws NoSuchMethodException, InvocationTargetException, IllegalAccessException
{
Class<?> clazz = View.class;
Method method = clazz.getMethod(methodName, Drawable.class);
// Allowing non-public access call to this method.
method.setAccessible(true);
method.invoke(receiverObject, background);
}
}
我的自定义渐变
/**
* I am extending the GradientDrawable just for fun, and also
* because I want to set the shader property for this drawable,
* you could, however, use the GradientDrawable directly.
*/
public class Gradient extends GradientDrawable {
private Paint paint;
private LinearGradient gradient;
public Gradient()
{
super();
// check the docs for LinearGradient for these parameters
gradient = new LinearGradient(0,0, 100, 100, Color.BLUE, Color.GREEN, Shader.TileMode.REPEAT);
paint = new Paint();
paint.setShader(gradient);
}
public Gradient(GradientDrawable.Orientation orientation, int[] colors)
{
super(orientation, colors);
gradient = new LinearGradient(0,0, 100, 100, Color.BLUE, Color.GREEN, Shader.TileMode.REPEAT);
paint = new Paint();
paint.setShader(gradient);
}
@Override
public void draw(Canvas canvas)
{
canvas.drawPaint(paint);
}
}
按钮的初始背景
<?xml version="1.0" encoding="utf-8"?>
<!-- The initial shape with just a solid yellow color -->
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<solid
android:color="#ff0"/>
</shape>
哈,我没有使用 Reflections,而是根据当前版本使用这段代码来设置适当的背景
int sdk = android.os.Built.VERSION.SDK_INT;
if(sdk < android.os.Build.VERSION_CODES.JELLY_BEAN) {
setBackgroundDrawable();
} else {
setBackground();
}