[C#]-利用clipboard轉換office內容物為圖片

最近接了一個case，
在office上選取物件利用ctrl+c複製物件到clipboard內，
並在picturebox控制項上利用ctrl+v將物件從clipboard取出，
並以圖片形式顯示在picturebox上，
最後將picturebox上的image存成圖片檔。

首先先記錄一下如何判斷鍵盤的組合鍵，如下:

private void Form1_KeyDown(object sender, KeyEventArgs e)
{
    switch (e.KeyData)
    {
        case (Keys.Control | Keys.V):
            // do something 
            break;
    }
}

接下來的重點是從clipboard內取出物件時必須知道它支援那些格式，
我們可以利用下面的方式知道該物件所支援的格式有那些:

foreach (string format in Clipboard.GetDataObject().GetFormats())
{
    // do something
}

也有一些簡便的方式，例如Clipboard.ContainsText()或Clipboard.ContainsImage()等可以判斷。

再來我們準備一些method來從clipboard中取出office中大部份常見的格式。
Bitmap格式的物件，我們都能用下面的方式取得image:

public void CatchBitmap()
{
    this.pictureBox1.Image = (Bitmap)Clipboard.GetImage();
}

這裡遇到比較麻煩的困難點是EnhancedMetafile格式，
必須要用win32裡的API去取得系統的clipboard來使用，方式如下:

public const uint CF_METAFILEPICT = 3;
public const uint CF_ENHMETAFILE = 14;

[DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)]
public static extern bool OpenClipboard(IntPtr hWndNewOwner);

[DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)]
public static extern bool CloseClipboard();

[DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)]
public static extern IntPtr GetClipboardData(uint format);

[DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)]
public static extern bool IsClipboardFormatAvailable(uint format);

public void CatchEMF()
{
    if (OpenClipboard(this.Handle)) {
        if (IsClipboardFormatAvailable(CF_ENHMETAFILE))
        {
            IntPtr ptr = GetClipboardData(CF_ENHMETAFILE);
            if (!ptr.Equals(new IntPtr(0)))
            {
                Metafile metafile = new Metafile(ptr, true);
                //Set the Image Property of PictureBox 
                this.pictureBox1.Image = metafile;
            }
        }
        CloseClipboard();
    }
}

再來如果copy放進clipboard內的是純文字物件的話，
就必須要用Graphics來drawing string才能產生圖檔，如下:

public void DrawString()
{
    String sImageText = Clipboard.GetText();
    Bitmap objBmpImage = new Bitmap(1, 1);

    int intWidth = 0;
    int intHeight = 0;

    // Create the Font object for the image text drawing.
    Font objFont = 
        new Font("Arial", 20, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Pixel);

    // Create a graphics object to measure the text's width and height.
    Graphics objGraphics = Graphics.FromImage(objBmpImage);

    // This is where the bitmap size is determined.
    intWidth = (int)objGraphics.MeasureString(sImageText, objFont).Width;
    intHeight = (int)objGraphics.MeasureString(sImageText, objFont).Height;

    // Create the bmpImage again with the correct size for the text and font.
    objBmpImage = new Bitmap(objBmpImage, new Size(intWidth, intHeight));

    // Add the colors to the new bitmap.
    objGraphics = Graphics.FromImage(objBmpImage);

    // Set Background color
    objGraphics.Clear(Color.White);
    objGraphics.SmoothingMode = SmoothingMode.AntiAlias;
    objGraphics.TextRenderingHint = TextRenderingHint.AntiAlias;
    objGraphics.DrawString(sImageText, objFont, 
        new SolidBrush(Color.FromArgb(102, 102, 102)), 0, 0);
    objGraphics.Flush();
    this.pictureBox1.Image = objBmpImage;
}

接下來下面要講解的功能是如何把在excel內選取的cells自動轉換成對應的chart圖，
基本上複製的cells放進clipboard本身就支援Bitmap格式，
但直接取用會直接像剪貼那樣，如果要轉換成對應的chart圖則必須再行判斷，
這裡是利用Microsoft.Office.Interop.Excel來轉換，範例碼如下:

public void Convert()
{
    IDataObject iData = Clipboard.GetDataObject();
    String cellArea = (String)iData.GetData(DataFormats.Text);
    String[] rows = cellArea.Split(new Char[] { '\n' });

    Excel.Application xlApp;
    Excel.Workbook xlWorkBook;
    Excel.Worksheet xlWorkSheet;
    object misValue = System.Reflection.Missing.Value;

    xlApp = new Excel.ApplicationClass();
    xlWorkBook = xlApp.Workbooks.Add(misValue);
    xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);

    int rowLength = rows.Length;
    int rowCount = 1;
    int cellCount = 1;
    int maxCellCount = 1;
    
    foreach (String line in rows)
    {
        if (rowCount == rowLength)
        {
            break;
        }
        String[] cells = line.Split(null);
        int cellLength = cells.Length;
        foreach (String cell in cells)
        {
            if (cellCount == cellLength)
            {
                break;
            }
            if (cellCount > maxCellCount)
            {
                maxCellCount++;
            }
            xlWorkSheet.Cells[rowCount, cellCount] = cell;
            cellCount++;
        }
        rowCount++;
        cellCount = 1;
    }

    Excel.Range chartRange;

    Excel.ChartObjects xlCharts = (Excel.ChartObjects)xlWorkSheet.ChartObjects(Type.Missing);
    Excel.ChartObject myChart = (Excel.ChartObject)xlCharts.Add(10, 80, 300, 250);
    Excel.Chart chartPage = myChart.Chart;

    rowCount--;
    maxCellCount--;
    String endCorner = map.ElementAt(maxCellCount).Value;
    endCorner = endCorner + rowCount.ToString();
    
    // endCorner的格式例如:c7，就是cells右下角的範圍邊界點
    chartRange = xlWorkSheet.get_Range("A1", endCorner);
    chartPage.SetSourceData(chartRange, misValue);
    // 設定繪製的chart圖型式
    chartPage.ChartType = Excel.XlChartType.xlColumnClustered;
    chartPage.CopyPicture(Excel.XlPictureAppearance.xlScreen,
                          Excel.XlCopyPictureFormat.xlBitmap,
                          Excel.XlPictureAppearance.xlScreen);
    xlWorkBook.Close(false, false, misValue);
}

產生的chart圖會利用copy放進clipboard內。

使用畫面如下，紅色框部份就是被選取的cells，當在picturebox上按下ctrl+v時，
就會利用office元件繪製chart圖:

最後就是整理一些條件判斷式，來處理當遇到什樣格式時要執行那一個method比較恰當:

// 一般的圖檔
if (this.formatList.Contains("Bitmap") && !this.formatList.Contains("Text"))
{
    CatchBitmap();
}
// excel的cells欄位集合
else if (this.formatList.Contains("Bitmap") && this.formatList.Contains("Text"))
{
    // if want to create chart
    Convert();
                
    // offic 2003
    CatchBitmap();
                   
    // offic 2007
    CatchEMF();
}
// 純粹選取文字
else if (!this.formatList.Contains("Bitmap") && this.formatList.Contains("Text"))
{
    DrawString();
}
// excel2003的chart，只有emf格式，最後再處理
else if (this.formatList.Contains("EnhancedMetafile"))
{
    CatchEMF();
}