五、基本界面控件-3图片控件

5.3 图片控件

5.3.1 ImageView

图5.3.1ImageView

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android.widget.ImageView图片控件，继承自android.view.View，在android.widget包中。

最简单的使用方法。src设置图片路径，可引用drawable的图片。

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<ImageView android:layout_width="wrap_content" 
		   android:layout_height="wrap_content"
		   android:src="@drawable/tool"/>

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动态声明ImageView，设置src。

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try {
	ImageView imageView = new ImageView(this);
	InputStream inputStream = super.getAssets().open("home.png");
	imageView.setImageDrawable(Drawable.createFromStream(inputStream, "tackpic"));
	this.imageLayout.addView(imageView, new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,
			LinearLayout.LayoutParams.WRAP_CONTENT));
} catch (IOException e) {
	e.printStackTrace();
}

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5.3.2 ImageButton

图5.3.2ImageButton

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android.widget.ImageButton图片控件，继承自android.widget.ImageView，在android.widget包中。

最简单的使用方法。src设置图片路径，可引用drawable的图片。

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<ImageButton android:layout_width="wrap_content" 
		     android:layout_height="wrap_content"
		     android:src="@drawable/but_01"/>

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动态声明ImageView，设置src。

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try {
	ImageButton imageButton = new ImageButton(this);
	InputStream inputStream = super.getAssets().open("but_02.png");
	imageButton.setImageDrawable(Drawable.createFromStream(inputStream, "tackpic"));
	this.imageLayout.addView(imageButton, new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,
			LinearLayout.LayoutParams.WRAP_CONTENT));
} catch (IOException e) {
	e.printStackTrace();
}

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5.3.3 ImageSwitcher和Gallery

图5.3.3 ImageSwitcher

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android.widget. ImageSwitcher图片控件，继承自android.widget.ViewSwitcher（ViewGroup）。在android.widget包中。

ImageSwithcer是用来图片显示那块区域的控件，使用方法setInAnimation(Animation)，setOutAnimation(Animation)设置动画。

Gallery是来控制底下那个图标索引列表索引用的。ImageAdapter继承自BaseAdapter，设置Gallery的适配器。

在layout添加ImageSwitcher和Gallery。定义Activity，implements接口OnItemSelectedListener, ViewFactory。onCreate的时候定义要显示图片路径列表，设置Gallery的Adapter。onItemSelected事件触发时，设置对应的图片。

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Layout文件。

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<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
				android:layout_width="fill_parent" 
				android:layout_height="fill_parent">
				
	<ImageSwitcher android:id="@+id/switcher"
				   android:layout_width="fill_parent" 
				   android:layout_height="fill_parent"
				   android:layout_alignParentTop="true" 
				   android:layout_alignParentLeft="true" />

	<Gallery android:id="@+id/gallery" 
			 android:background="#55000000"
			 android:layout_width="fill_parent" 
			 android:layout_height="60dp"
			 android:layout_alignParentBottom="true"
			 android:layout_alignParentLeft="true" 
			 android:gravity="center_vertical"
			 android:spacing="16dp" />

</RelativeLayout>

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SwitcherActivity类。

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public class SwitcherActivity extends Activity implements OnItemSelectedListener, ViewFactory {

	private ImageSwitcher imageSwitcher;
	private Gallery gallery;

	private ArrayList<String> imageAssetPathList = new ArrayList<String>();

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		super.setContentView(R.layout.switcher);
		this.imageSwitcher = (ImageSwitcher) findViewById(R.id.switcher);
		this.gallery = (Gallery) findViewById(R.id.gallery);

		for (int i = 1; i <= 20; i++) {
			this.imageAssetPathList.add("images/" + i + ".jpg");
		}

		this.imageSwitcher.setFactory(this);
		this.gallery.setAdapter(new ImageAdapter(this, this.imageAssetPathList));
		this.gallery.setOnItemSelectedListener(this);

	}

	@Override
	public View makeView() {
		ImageView imageView = new ImageView(this);
		imageView.setBackgroundColor(0xFF000000);
		imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);
		imageView.setLayoutParams(new ImageSwitcher.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
		return imageView;
	}

	@Override
	public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
		try {
			InputStream inputStream = super.getAssets().open(this.imageAssetPathList.get(position));
			imageSwitcher.setImageDrawable(Drawable.createFromStream(inputStream, "" + position));
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	@Override
	public void onNothingSelected(AdapterView<?> parent) {

	}

}

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ImageAdapter类

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public class ImageAdapter extends BaseAdapter {

	private Context content;
	private ArrayList<String> imageAssetPathList;

	public ImageAdapter(Context content, ArrayList<String> imageAssetPathList) {
		this.content = content;
		this.imageAssetPathList = imageAssetPathList;
	}

	@Override
	public int getCount() {
		if (this.imageAssetPathList != null) {
			return this.imageAssetPathList.size();
		} else {
			return 0;
		}
	}

	@Override
	public Object getItem(int position) {
		return null;
	}

	@Override
	public long getItemId(int position) {
		return 0;
	}

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		try {
			ImageView imageView;
			imageView = new ImageView(this.content);
			imageView.setAdjustViewBounds(true);
			imageView.setScaleType(ImageView.ScaleType.FIT_XY);
			imageView.setPadding(0, 0, 0, 0);

			InputStream inputStream = this.content.getAssets().open(this.imageAssetPathList.get(position));
			imageView.setImageDrawable(Drawable.createFromStream(inputStream, "" + position));

			return imageView;
		} catch (IOException e) {
			e.printStackTrace();
			return null;
		}
	}

}

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