c# - 如何将复选框作为 dataGridView 的 ColumnHeader

Question

我正在使用 C# VS2005 开发一个窗口应用程序。我有一个 dataGridView，其中第一列有复选框。现在我希望列标题也成为一个复选框，如果我选择列中的所有 Checkboxex 应该被选中。我怎样才能做到这一点。？我提到了 Code Project link

但是如果我使用它，如果我单击 FirstCell(不是页眉)，下面的所有单元格都会被选中。但我想在列标题中有一个复选框。我该怎么做？

Answer 1

我还需要在 DataGridView 列的列标题中有一个 CheckBox。这是我的做法:

• 创建一个继承自 DataGridViewColumnHeaderCell 的类
• 在内部使用 System.Windows.Forms.CheckBox 来存储选中状态并提供操作系统风格的视觉 CheckBox 表示。
• 使用 Bitmap 作为缓冲区并在其上绘制常规 CheckBox(使用 CheckBox.DrawToBitmap)
• 重写 DataGridViewColumnHeaderCell.Paint，如有必要，在将缓冲区绘制到 Paint 提供的 Graphics 之前更新缓冲区
• 在派生的 DataGridViewColumnHeaderCell 上提供一个 Checked 属性，以及一个 CheckedChanged 事件
• 在填充 DataGridView 时，在列的 HeaderCell 中替换派生的 DataGridViewColumnHeaderCell。
• 在单击列标题时选中和取消选中 CheckBox，前提是鼠标单击在 CheckBox 的范围内
• 通过监听 CheckedChanged 事件，更新底层数据对象，然后调用 ResetBindings 来更新DataGridView

这是我编写的派生自 DataGridViewColumnHeaderCell 的类:

class DataGridViewCheckBoxColumnHeaderCell : DataGridViewColumnHeaderCell
{
    private Bitmap buffer;
    private CheckBox checkBox;
    private Rectangle checkBoxBounds;

    public DataGridViewCheckBoxColumnHeaderCell()
    {
        this.checkBox = new CheckBox();
    }

    public event EventHandler CheckedChanged;

    public bool Checked
    {
        get 
        { 
            return this.checkBox.Checked; 
        }

        set
        {
            if (!this.Checked == value)
            {
                this.checkBox.Checked = value;
                if (this.buffer != null)
                {
                    this.buffer.Dispose();
                    this.buffer = null;
                }

                this.OnCheckedChanged(EventArgs.Empty);

                if (this.DataGridView != null)
                {
                    this.DataGridView.Refresh();
                }
            }
        }
    }

    protected override void Paint(
        Graphics graphics, 
        Rectangle clipBounds, 
        Rectangle cellBounds, 
        int rowIndex, 
        DataGridViewElementStates dataGridViewElementState, 
        object value, 
        object formattedValue, 
        string errorText, 
        DataGridViewCellStyle cellStyle, 
        DataGridViewAdvancedBorderStyle advancedBorderStyle, 
        DataGridViewPaintParts paintParts)
    {
        // Passing String.Empty in place of 
        // value and formattedValue prevents 
        // this header cell from having text.

        base.Paint(
            graphics, 
            clipBounds, 
            cellBounds, 
            rowIndex, 
            dataGridViewElementState, 
            String.Empty, 
            String.Empty, 
            errorText, 
            cellStyle, 
            advancedBorderStyle, 
            paintParts);

        if (this.buffer == null 
            || cellBounds.Width != this.buffer.Width
            || cellBounds.Height != this.buffer.Height)
        {
            this.UpdateBuffer(cellBounds.Size);
        }

        graphics.DrawImage(this.buffer, cellBounds.Location);
    }

    protected override Size GetPreferredSize(
        Graphics graphics, 
        DataGridViewCellStyle cellStyle, 
        int rowIndex, 
        Size constraintSize)
    {
        return this.checkBox.GetPreferredSize(constraintSize);
    }

    protected override void OnMouseClick(DataGridViewCellMouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left 
            && this.checkBoxBounds.Contains(e.Location))
        {
            this.Checked = !this.Checked;
        }

        base.OnMouseClick(e);
    }

    private void UpdateBuffer(Size size)
    {
        Bitmap updatedBuffer = new Bitmap(size.Width, size.Height);

        this.checkBox.Size = size;

        if (this.checkBox.Size.Width > 0 && this.checkBox.Size.Height > 0)
        {
            Bitmap renderedCheckbox = new Bitmap(
                this.checkBox.Width, 
                this.checkBox.Height);

            this.checkBox.DrawToBitmap(
                renderedCheckbox, 
                new Rectangle(new Point(), this.checkBox.Size));

            MakeTransparent(renderedCheckbox, this.checkBox.BackColor);
            Bitmap croppedRenderedCheckbox = AutoCrop(
                renderedCheckbox, 
                Color.Transparent);

            // TODO implement alignment, right now it is always
            // MiddleCenter regardless of this.Style.Alignment

            this.checkBox.Location = new Point(
                (updatedBuffer.Width - croppedRenderedCheckbox.Width) / 2, 
                (updatedBuffer.Height - croppedRenderedCheckbox.Height) / 2);

            Graphics updatedBufferGraphics = Graphics.FromImage(updatedBuffer);
            updatedBufferGraphics.DrawImage(
                croppedRenderedCheckbox, 
                this.checkBox.Location);

            this.checkBoxBounds = new Rectangle(
                this.checkBox.Location, 
                croppedRenderedCheckbox.Size);

            renderedCheckbox.Dispose();
            croppedRenderedCheckbox.Dispose();
        }

        if (this.buffer != null)
        {
            this.buffer.Dispose();
        }

        this.buffer = updatedBuffer;
    }

    protected virtual void OnCheckedChanged(EventArgs e)
    {
        EventHandler handler = this.CheckedChanged;
        if (handler != null)
        {
            handler(this, e);
        }
    }

    // The methods below are helper methods for manipulating Bitmaps

    private static void MakeTransparent(Bitmap bitmap, Color transparencyMask)
    {
        int transparencyMaskArgb = transparencyMask.ToArgb();
        int transparentArgb = Color.Transparent.ToArgb();

        List deadColumns = new List();

        for (int x = 0; x = 0; x--)
        {
            if (deadColumns.Count == bitmap.Height)
            {
                break;
            }

            for (int y = bitmap.Height - 1; y >= 0; y--)
            {
                if (deadColumns.Contains(y))
                {
                    continue;
                }

                int pixel = bitmap.GetPixel(x, y).ToArgb();

                if (pixel == transparencyMaskArgb)
                {
                    bitmap.SetPixel(x, y, Color.Transparent);
                }
                else if (pixel != transparentArgb)
                {
                    deadColumns.Add(y);
                    break;
                }
            }
        }
    }

    public static Bitmap AutoCrop(Bitmap bitmap, Color backgroundColor)
    {
        Size croppedSize = bitmap.Size;
        Point cropOrigin = new Point();
        int backgroundColorToArgb = backgroundColor.ToArgb();

        for (int x = bitmap.Width - 1; x >= 0; x--)
        {
            bool allPixelsAreBackgroundColor = true;
            for (int y = bitmap.Height - 1; y >= 0; y--)
            {
                if (bitmap.GetPixel(x, y).ToArgb() != backgroundColorToArgb)
                {
                    allPixelsAreBackgroundColor = false;
                    break;
                }
            }

            if (allPixelsAreBackgroundColor)
            {
                croppedSize.Width--;
            }
            else
            {
                break;
            }
        }

        for (int y = bitmap.Height - 1; y >= 0; y--)
        {
            bool allPixelsAreBackgroundColor = true;
            for (int x = bitmap.Width - 1; x >= 0; x--)
            {
                if (bitmap.GetPixel(x, y).ToArgb() != backgroundColorToArgb)
                {
                    allPixelsAreBackgroundColor = false;
                    break;
                }
            }

            if (allPixelsAreBackgroundColor)
            {
                croppedSize.Height--;
            }
            else
            {
                break;
            }
        }

        for (int x = 0; x = 0 && xWhole = 0)
                {
                    bitmapSection.SetPixel(x, y, bitmap.GetPixel(xWhole, yWhole));
                }
                else
                {
                    bitmapSection.SetPixel(x, y, Color.Transparent);
                }
            }
        }

        return bitmapSection;
    }
}