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控件实例合集

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Android系统默认为我们提供了许多控件,这些控件在我们写一些程序时非常实用,你是否对这些控件的使用都了如指掌了呢?本例子列举了部分我们常用的控件,包括按钮,文本控件,单选,复选,图形,时间控件等等。
首先看一下例子中包含的所有控件:

02_widgetdemo

这个界面是由程序根据屏幕大小自动计算出来的,在不同的设备运行,界面可能会发生变化,请注意。
界面的DashboardLayout代码:

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
     mMaxChildWidth = 0;
     mMaxChildHeight = 0;

     final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( MeasureSpec.getSize(widthMeasureSpec), MeasureSpec.AT_MOST);
     final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec( MeasureSpec.getSize(heightMeasureSpec), MeasureSpec.AT_MOST);

     final int count = getChildCount();
     for (int i = 0; i < count; i++) {
          final View child = getChildAt(i);
          if (child.getVisibility() == GONE) {
               continue;
          }

          child.measure(childWidthMeasureSpec, childHeightMeasureSpec);

          mMaxChildWidth = Math.max(mMaxChildWidth, child.getMeasuredWidth());
          mMaxChildHeight = Math.max(mMaxChildHeight,
          child.getMeasuredHeight());
     }

     setMeasuredDimension(resolveSize(mMaxChildWidth, widthMeasureSpec),
     resolveSize(mMaxChildHeight, heightMeasureSpec));
}

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
     int width = r - l;
     int height = b - t;

     final int count = getChildCount();

     // Calculate the number of visible children.
     int visibleCount = 0;
     for (int i = 0; i < count; i++) {
          final View child = getChildAt(i);
          if (child.getVisibility() == GONE) {
               continue;
          }
          ++visibleCount;
     }

     if (visibleCount == 0) {
          return;
     }

     // Calculate what number of rows and columns will optimize for even
     // horizontal and
     // vertical whitespace between items. Start with a 1 x N grid, then try
     // 2 x N, and so on.
     int bestSpaceDifference = Integer.MAX_VALUE;
     int spaceDifference;

     // Horizontal and vertical space between items
     int hSpace = 0;
     int vSpace = 0;

     int cols = 1;
     int rows;

     while (true) {
          rows = (visibleCount - 1) / cols + 1;

          hSpace = ((width - mMaxChildWidth * cols) / (cols + 1));
          vSpace = ((height - mMaxChildHeight * rows) / (rows + 1));

          spaceDifference = Math.abs(vSpace - hSpace);
          if (rows * cols != visibleCount) {
                spaceDifference *= UNEVEN_GRID_PENALTY_MULTIPLIER;
          } else if (rows * mMaxChildHeight > height || cols * mMaxChildWidth > width) {
                spaceDifference *= UNEVEN_GRID_PENALTY_MULTIPLIER;
          }

          if (spaceDifference < bestSpaceDifference) {
                // Found a better whitespace squareness/ratio
                bestSpaceDifference = spaceDifference;

                // If we found a better whitespace squareness and there's only 1
                // row, this is
                // the best we can do.
                if (rows == 1) {
                      break;
                }
           } else {
                // This is a worse whitespace ratio, use the previous value of
                // cols and exit.
                --cols;
                rows = (visibleCount - 1) / cols + 1;
                hSpace = ((width - mMaxChildWidth * cols) / (cols + 1));
                vSpace = ((height - mMaxChildHeight * rows) / (rows + 1));
                break;
           }

           ++cols;
      }

      // Lay out children based on calculated best-fit number of rows and
      // cols.

      // If we chose a layout that has negative horizontal or vertical space,
      // force it to zero.
      hSpace = Math.max(0, hSpace);
      vSpace = Math.max(0, vSpace);

      // Re-use width/height variables to be child width/height.
      width = (width - hSpace * (cols + 1)) / cols;
      height = (height - vSpace * (rows + 1)) / rows;

      int left, top;
      int col, row;
      int visibleIndex = 0;
      for (int i = 0; i < count; i++) {
            final View child = getChildAt(i);
            if (child.getVisibility() == GONE) {
                  continue;
            }

            row = visibleIndex / cols;
            col = visibleIndex % cols;

            left = l + hSpace * (col + 1) + width * col;
            top = t + vSpace * (row + 1) + height * row;

            child.layout(left, top, (hSpace == 0 && col == cols - 1) ? r
                  : (left + width), (vSpace == 0 && row == rows - 1) ? b
                  : (top + height));
            ++visibleIndex;
      }
}

textview的例子:

02_widgetdemo2

editview的例子:

02_widgetdemo3

源码下载:点击下载

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