如何调整e.Graphics将在其中绘制的区域（视口）？

Question

我正在使用PrintDocument.Print()启动打印过程，在其中打印数据网格（C1FlexGrid）以及一些页眉和页脚信息。 这是一个有点复杂的打印过程。 我正在使用标准的PrintDocument方法，但是由于要在页面上显示内容，因此我可以控制所有发生的事情。

我遇到的问题是我想缩小将绘制网格控件的区域。 当我绘制页眉和页脚时，我正在计算它们将消耗的空间，以及网格要占用的空间。 网格控件具有自己的PrintDocumentGridRenderer类，该类提供PrintPage()方法，我调用该方法来获取它以在PrintDocument的Graphics对象上呈现网格。

我无法弄清楚如何限制网格可以容纳的区域，但是在绘制了页眉/页脚并知道剩余空间后再进行操作。

这是一些代码，我认为这是本质：

private void PrintDocument_PrintPage(Object sender, PrintPageEventArgs e)
{
    //I tried putting a non-drawing version of DrawHeadersAndFooters() here to get the calculated space and then reset the Margin...but it's always one call behind the Graphics object, meaning that it has no effect on the first page.  In fact, because Setup() gets called with two different margins at that point, the pages end up very badly drawn.

    _gridRenderer.Setup(e);  //this is the PrintDocumentGridRender object and Setup() figures out page layout (breaks and such)

    DrawHeadersAndFooters(e.Graphics, e.MarginBounds);
    Int32 newX = _printProperties.GridBounds.X - e.MarginBounds.X;
    Int32 newY = _printProperties.GridBounds.Y - e.MarginBounds.Y;
    e.Graphics.TranslateTransform(newX, newY);
    _gridRenderer.PrintPage(e, _currentPage - 1);  //grid control's print method
    e.HasMorePages = _currentPage < _printProperties.Document.PrinterSettings.ToPage;
    _currentPage++;
}

private void DrawHeadersAndFooters(Graphics graphics, Rectangle marginBounds)
{
    Rectangle textRect = new Rectangle();
    Int32 height = 0;
    //loop lines in header paragraph to get total height required
    //there are actually three, across the page, but just one example for bevity...
    if (!String.IsNullOrEmpty(_printProperties.HeaderLeft))
    {
        Int32 h = 0;
        foreach (String s in _printProperties.HeaderLeft.Split(new String[] { "\r\n" }, StringSplitOptions.RemoveEmptyEntries))
            h += (Int32)graphics.MeasureString(s, _printProperties.HeaderLeftFont, width, stringFormat).Height;
        height = (h > height) ? h : height;
    } //repeat for other two, keeping the greatest of 3 heights in the end
    textRect.X = marginBounds.X;
    textRect.Y = (Int32)_printProperties.Document.DefaultPageSettings.PrintableArea.Y;  //a global storage for printing information I need to keep in memory
    textRect.Width = width;
    textRect.Height = height;

    stringFormat.Alignment = StringAlignment.Near;
    graphics.DrawString(_printProperties.HeaderLeft, _printProperties.HeaderLeftFont, new SolidBrush(_printProperties.HeaderLeftForeColor), textRect, stringFormat);

    _printProperties.GridBounds = new Rectangle(marginBounds.X, textRect.Y, marginBounds.Width, marginBounds.Bottom - textRect.Y);  //here I think I have the space into which the grid _should_ be made to fit
}

您可以看到在PrintDocument_PrintPage()我正在对Graphics对象应用转换，该转换将网格向下滑动到适当位置，并且位于标题下方。

截图：

因此，问题是：

我想自下而上缩小区域，以使该网格的底部位于页脚上方。 通过查看右下角，可以看到渲染的网格图像与我已经绘制的页脚重叠。 这就是我需要的帮助。 我如何不做ScaleTransform()类的事情而缩小Graphics绘图空间，这似乎根本不是个正确的主意。

Answer 1

答案被证明是对逻辑的完全重组。 我没有尝试全部弄清楚并同时渲染它，而是将计算代码重构为一个单独的方法，可以在调用PrintDocument.Print()之前调用PrintDocument.Print() 。

一切都归结为我以前没有意识到的这个小宝石：

Graphics graphics = _printProperties.Document.PrinterSettings.CreateMeasurementGraphics();

这为打印文档提供了一个新的Graphics对象，可用于在打印之前进行所有计算。 一旦有了这些，就可以简单地存储它，然后在实际的页眉和页脚渲染中使用结果。

它还为我提供了在网格的Print()调用之前调整PrintDocument.DefaultPageSettings的Margins所需的信息。

一些代码供参考：

//The margins I intend to adjust
System.Drawing.Printing.Margins margins = _printProperties.Document.DefaultPageSettings.Margins;

//Get paper width/height respecting orientation
Int32 paperWidth = 
    _printProperties.Document.DefaultPageSettings.Landscape ? 
    _printProperties.Document.DefaultPageSettings.PaperSize.Height : 
    _printProperties.Document.DefaultPageSettings.PaperSize.Width;
Int32 paperHeight = 
    _printProperties.Document.DefaultPageSettings.Landscape ? 
    _printProperties.Document.DefaultPageSettings.PaperSize.Width : 
    _printProperties.Document.DefaultPageSettings.PaperSize.Height;

//Calculate printable bounds using user-defined margins and paper size
Rectangle marginBounds = new Rectangle(_printProperties.MarginLeft, _printProperties.MarginTop,
    paperWidth - (_printProperties.MarginLeft + _printProperties.MarginRight),
    paperHeight - (_printProperties.MarginTop + _printProperties.MarginBottom));

//Calculate Rectangles for every header/footer element
CalculatePrintRegions(marginBounds);

//If certain elements exist, use the calculated sizes to adjust the margins
Boolean hasHeader =
    !String.IsNullOrEmpty(_printProperties.HeaderLeft) ||
    !String.IsNullOrEmpty(_printProperties.HeaderCenter) ||
    !String.IsNullOrEmpty(_printProperties.HeaderRight);
Boolean hasHeader2 = 
    !String.IsNullOrEmpty(_printProperties.Header2Range) || 
    !String.IsNullOrEmpty(_printProperties.Header2Date);
Boolean hasFooter =
    !String.IsNullOrEmpty(_printProperties.FooterLeft) ||
    !String.IsNullOrEmpty(_printProperties.FooterCenter) ||
    !String.IsNullOrEmpty(_printProperties.FooterRight);
if (hasHeader)
{
    Int32 topAdd = Math.Max(Math.Max(_printProperties.HeaderLeftRect.Height, _printProperties.HeaderCenterRect.Height), _printProperties.HeaderRightRect.Height);
    if (hasHeader2)
        topAdd += Math.Max(_printProperties.Header2RangeRect.Height, _printProperties.Header2DateRect.Height);
    margins.Top = _printProperties.HeaderLeftRect.Top + topAdd + 10;
}
if (hasFooter)
    margins.Bottom = paperHeight - (_printProperties.FooterLeftRect.Top - 10);

//This used to be the starting point, everything above was added in answer to the problem
_printProperties.IsPrinting = true;  //used by drawing code to control drawing of certain elements (such as not showing selection/highlight)
_printProperties.IsPreview = Preview;
_printProperties.IsDryRun = true;  //to get page count into _gridRenderer before displaying prompt
_printProperties.Document.Print();

请注意，由于我是手动绘制所有页眉/页脚文本，因此页边距对此没有任何影响，因此调整它们只会影响网格渲染。