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众所周知,android可以通过XML文件来创建selector,以Drawable对象的形式安装到组件上,以提供统一的风格设置。但是在某些时候,我们需要通过代码的形式来实现相同的功能,例如组件数量非常多,对应不同的图片,这时候如果还用XML的话就需要创建大量的selector文件,非常繁琐。
例如一个TextView使用了如下的selector
<TextViewandroid:id="@+id/TextView_title"android:layout_width="wrap_content"android:layout_height="wrap_content"android:focusable="true"android:drawableTop="@drawable/selector_tabwidget_icon"android:textAlignment="center"/>
<selector xmlns:android="http://schemas.android.com/apk/res/android" ><!-- Non focused states --><item android:state_focused="false" android:state_selected="false" android:state_pressed="false" android:drawable="@drawable/contact" /><item android:state_focused="false" android:state_selected="true" android:state_pressed="false" android:drawable="@drawable/contact_sel" /><!-- Focused states --><item android:state_focused="true" android:state_selected="false" android:state_pressed="false" android:drawable="@drawable/contact_sel" /><item android:state_focused="true" android:state_selected="true" android:state_pressed="false" android:drawable="@drawable/contact_sel" /><!-- Pressed --><item android:state_selected="true" android:state_pressed="true" android:drawable="@drawable/contact_sel" /><item android:state_pressed="true" android:drawable="@drawable/contact_sel" />
</selector>
里面所引用的图片资源文件非常多,如果每个文件都对应一个XML的文件的话,就会非常繁琐,修改起来非常麻烦。
实际上,所有XML设定能做的事情,android里同样可以用编码的方式来实现,像上面那个XML文件,就可以就下面的代码来实现:
StateListDrawable drawable = new StateListDrawable();//Non focused statesdrawable.addState(new int[]{-android.R.attr.state_focused, -android.R.attr.state_selected, -android.R.attr.state_pressed},getResources().getDrawable(R.drawable.contact));drawable.addState(new int[]{-android.R.attr.state_focused, android.R.attr.state_selected, -android.R.attr.state_pressed},getResources().getDrawable(R.drawable.contact_sel));//Focused statesdrawable.addState(new int[]{android.R.attr.state_focused,-android.R.attr.state_selected, -android.R.attr.state_pressed},getResources().getDrawable(R.drawable.contact_sel));drawable.addState(new int[]{android.R.attr.state_focused,android.R.attr.state_selected, -android.R.attr.state_pressed},getResources().getDrawable(R.drawable.contact_sel));//Presseddrawable.addState(new int[]{android.R.attr.state_selected, android.R.attr.state_pressed},getResources().getDrawable(R.drawable.contact_sel));drawable.addState(new int[]{android.R.attr.state_pressed},getResources().getDrawable(R.drawable.contact_sel));TextView textView = (TextView) findViewById(R.id.TextView_title);textView.setCompoundDrawablesWithIntrinsicBounds(null, drawable, null, null);
注意里面的“-”号,当XML的设定是false时,就需要使用资源符号的负值来设定
- package lab.sodino.statelist;
- import android.app.Activity;
- import android.content.Context;
- import android.content.res.ColorStateList;
- import android.graphics.drawable.Drawable;
- import android.graphics.drawable.StateListDrawable;
- import android.os.Bundle;
- import android.view.View;
- import android.view.View.OnClickListener;
- import android.widget.TextView;
- /**
- * 对TextView设置ColorStateList使其在Normal、Pressed、Focused、Unable四种状态下显示不同的颜色。<br/>
- * StateListDrawable可直接使用图片应用在相似场合。
- */
- public class ActColorStateList extends Activity implements OnClickListener {
- private TextView txtShow;
- public void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.main);
- txtShow = (TextView) findViewById(R.id.txtShow);
- txtShow.setText("Sodino\nNormal:0xffffffff\nPressed:0xffffff00\nFocused:0xff0000ff\nUnable:0xffff0000");
- txtShow.setTextColor(createColorStateList(0xffffffff, 0xffffff00, 0xff0000ff, 0xffff0000));
- txtShow.setOnClickListener(this);
- }
- /** 对TextView设置不同状态时其文字颜色。 */
- private ColorStateList createColorStateList(int normal, int pressed, int focused, int unable) {
- int[] colors = new int[] { pressed, focused, normal, focused, unable, normal };
- int[][] states = new int[6][];
- states[0] = new int[] { android.R.attr.state_pressed, android.R.attr.state_enabled };
- states[1] = new int[] { android.R.attr.state_enabled, android.R.attr.state_focused };
- states[2] = new int[] { android.R.attr.state_enabled };
- states[3] = new int[] { android.R.attr.state_focused };
- states[4] = new int[] { android.R.attr.state_window_focused };
- states[5] = new int[] {};
- ColorStateList colorList = new ColorStateList(states, colors);
- return colorList;
- }
- /** 设置Selector。 */
- public static StateListDrawable newSelector(Context context, int idNormal, int idPressed, int idFocused,
- int idUnable) {
- StateListDrawable bg = new StateListDrawable();
- Drawable normal = idNormal == -1 ? null : context.getResources().getDrawable(idNormal);
- Drawable pressed = idPressed == -1 ? null : context.getResources().getDrawable(idPressed);
- Drawable focused = idFocused == -1 ? null : context.getResources().getDrawable(idFocused);
- Drawable unable = idUnable == -1 ? null : context.getResources().getDrawable(idUnable);
- // View.PRESSED_ENABLED_STATE_SET
- bg.addState(new int[] { android.R.attr.state_pressed, android.R.attr.state_enabled }, pressed);
- // View.ENABLED_FOCUSED_STATE_SET
- bg.addState(new int[] { android.R.attr.state_enabled, android.R.attr.state_focused }, focused);
- // View.ENABLED_STATE_SET
- bg.addState(new int[] { android.R.attr.state_enabled }, normal);
- // View.FOCUSED_STATE_SET
- bg.addState(new int[] { android.R.attr.state_focused }, focused);
- // View.WINDOW_FOCUSED_STATE_SET
- bg.addState(new int[] { android.R.attr.state_window_focused }, unable);
- // View.EMPTY_STATE_SET
- bg.addState(new int[] {}, normal);
- return bg;
- }
- @Override
- public void onClick(View v) {
- if (v == txtShow) {
- txtShow.setEnabled(false);
- }
- }
- }
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