今天工作中又碰到个小问题，项目需要用到像Java Swing的JPanel一样带标题边框的布局，Android里没有类似控件，想到这个也不难，自己画了一个，是继承LinearLayout的一个自定义布局，当然，可以根据需要继承其他布局，基本都是一样的过程。
当然这个自定义布局有点瑕疵，就是标题占用了布局的一部分高度，子控件需要调整在布局中的垂直位置来避免和标题边框靠得过紧。
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下面贴代码：
/**
* 一个像java swing的JPanel控件一样可以带标题边框的布局，可以指定标题位置、颜色、字体大小。
* 另外还可以控制边框大小和边框的颜色。但是，子控件指定垂直布局适应的时候，子控件看起来并不在布局中间，
* 因为标题高度占用了布局的一部分垂直空间，使用时子控件需要指定Margin Top，否则可能和标题重叠。
*
* This is a layout with title border, you can set a title just like Java-Swing JPanel.
* and you can control the position, the color and the size of the title. In addition,
* the border's color and size are always controlled.
*
* !FIXME: The title has its own height, so when the children's gravity set as {@link Gravity#CENTER}
* or {@link Gravity#CENTER_VERTICAL} do not work well.
*
* @date 2013/09/24
* @author Wison
*/
public class TitleBorderLayout extends LinearLayout {
/** 默认情况下标题在总长度的1/10处显示 */
private static float DEFAULT_TITLE_POSITION_SCALE = 0.1f;
public static int DEFAULT_BORDER_SIZE = 1;
public static int DEFAULT_BORDER_COLOR = Color.GRAY;
public static int DEAFULT_TITLE_COLOR = Color.BLACK;
/** 边框面板的高度 */
private int mBorderPaneHeight ;
private Paint mBorderPaint;
private float mBorderSize;
private TextPaint mTextPaint;
private CharSequence mTitle;
private int mTitlePosition;
public TitleBorderLayout(Context context) {
this(context, null);
}
/**
* Construct a new TitleBorderLayout with default style, overriding specific style
* attributes as requested.
* @param context
* @param attrs
*/
public TitleBorderLayout(Context context, AttributeSet attrs) {
super(context, attrs);
setWillNotDraw(false);
mBorderPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mTextPaint = new TextPaint(Paint.ANTI_ALIAS_FLAG);
Resources res = getResources();
mTextPaint.density = res.getDisplayMetrics().density;
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.TitleBorderLayout);
mTitle = a.getText(R.styleable.TitleBorderLayout_title);
int titleColor = a.getColor(R.styleable.TitleBorderLayout_titleTextColor, DEAFULT_TITLE_COLOR);
mTextPaint.setColor(titleColor);
float titleTextSize = a.getDimension(R.styleable.TitleBorderLayout_titleTextSize, 0);
if (titleTextSize > 0) {
mTextPaint.setTextSize(titleTextSize);
}
mTitlePosition = a.getDimensionPixelSize(R.styleable.TitleBorderLayout_titlePosition, -1);
mBorderSize = a.getDimensionPixelSize(R.styleable.TitleBorderLayout_borderSize, DEFAULT_BORDER_SIZE);
int borderColor = a.getColor(R.styleable.TitleBorderLayout_borderColor, DEFAULT_BORDER_COLOR);
mBorderPaint.setColor(borderColor);
a.recycle();
}
/**
* Get the color of border.
* @return
*/
public int getBorderColor() {
return mBorderPaint.getColor();
}
/**
* Set the color of border.
* @param borderColor
*/
public void setBorderColor(int borderColor) {
mBorderPaint.setColor(borderColor);
requestLayout();
}
/**
* Get the size of border.
* @return
*/
public float getBorderSize() {
return mBorderSize;
}
/**
* Set the size of border.
* @param borderSize
*/
public void setBorderSize(float borderSize) {
mBorderSize = borderSize;
requestLayout();
}
/**
* Get the color of title.
* @return
*/
public int getTitleColor() {
return mTextPaint.getColor();
}
/**
* Set the color of title.
* @param titleColor
*/
public void setTitleColor(int titleColor) {
mTextPaint.setColor(titleColor);
requestLayout();
}
/**
* Get the size of title.
* @return
*/
public float getTitleTextSize() {
return mTextPaint.getTextSize();
}
/**
* Set the size of title.
* @param titleTextSize
*/
public void setTitleTextSize(float titleTextSize) {
mTextPaint.setTextSize(titleTextSize);
requestLayout();
}
/**
* Get the title.
* @return
*/
public CharSequence getTitle() {
return mTitle;
}
/**
* Set the title which will be shown on the top of border pane.
* @param title
*/
public void setTitle(CharSequence title) {
mTitle = title;
requestLayout();
}
/**
* Get the position of title.
* @return
*/
public int getTitlePosition() {
return mTitlePosition;
}
/**
* Set the position of title where the paint will start to draw.
* @param titlePosition
*/
public void setTitlePosition(int titlePosition) {
mTitlePosition = titlePosition;
requestLayout();
}
/**
* Get the height of border pane, it's different from the layout height!
* @return
*/
public int getBorderPaneHeight() {
return mBorderPaneHeight;
}
/**
* Draw the title border
* @param canvas
*/
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
FontMetrics fm = mTextPaint.getFontMetrics();
final float titleHeight = fm.descent - fm.ascent;
final CharSequence titleText = (mTitle == null) ? "" : mTitle;
final float titleWidth = Layout.getDesiredWidth(titleText, mTextPaint);
final int width = getWidth();
final int height = getHeight();
if (mTitlePosition <= 0 || mTitlePosition + titleWidth > width) {
mTitlePosition = (int) (DEFAULT_TITLE_POSITION_SCALE * width);
}
final float topBorderStartY = titleHeight / 3f - mBorderSize / 2;
mBorderPaneHeight = (int) Math.ceil(height - topBorderStartY);
/* 画标题边框 */
// 上
canvas.drawRect(0, topBorderStartY, mTitlePosition, topBorderStartY + mBorderSize, mBorderPaint);
canvas.drawText(titleText.toString(), mTitlePosition, titleHeight / 3 * 2f, mTextPaint); // 标题
canvas.drawRect(mTitlePosition + titleWidth, topBorderStartY, width, topBorderStartY + mBorderSize, mBorderPaint);
// 左
canvas.drawRect(0, topBorderStartY, mBorderSize, height, mBorderPaint);
// 右
canvas.drawRect(width - mBorderSize, topBorderStartY, width, height, mBorderPaint);
// 下
canvas.drawRect(0, height - mBorderSize, width, height, mBorderPaint);
}
}
以下为属性声明：
<declare-styleable name="TitleBorderLayout">
<!-- The title of BorderTitleLayout. -->
<attr name="title" format="string" />
<!-- The size of title. -->
<attr name="titleTextSize" format="dimension" />
<!-- The title start postion. -->
<attr name="titlePosition" format="dimension" />
<!-- The color of title. -->
<attr name="titleTextColor" format="reference|color" />
<!-- The size of border. -->
<attr name="borderSize" format="dimension" />
<!-- The color of border. -->
<attr name="borderColor" format="reference|color" />
</declare-styleable>
下面是效果图：
