How do I use PrintDocument with a scrollable panel`?
Here is some of my code:
MemoryImage = new Bitmap(pnl.Width, pnl.Height);
Rectangle rect = new Rectangle(0, 0, pnl.Width, pnl.Height);
pnl.DrawToBitmap(MemoryImage, new Rectangle(0, 0, pnl.Width,
pnl.Height));
Rectangle pagearea = e.PageBounds;
e.Graphics.DrawImage(MemoryImage, (pagearea.Width / 2) -
(pannel.Width / 2), pannel.Location.Y);
These sets of methods allow to print the content of a ScrollableControl to a Bitmap.
A description of the procedure:
control.AutoScrollPosition = new Point(0, 0); (an exception is raised otherwise: the Bitmap has a wrong size. You may want to store the current scroll position and restore it after).ScrollableControl.Controls collection and prints all first-level child controls in their relative position (a child Control's Bounds rectangle is relative to the container ClientArea.)DrawNestedControls recursive method, which will enumerate and draw all nested child Containers/Controls, preserving the internal clip bounds.Includes support for RichTextBox controls.
The RichEditPrinter class contains the logic required to print the content of a RichTextBox/RichEdit control. The class sends an EM_FORMATRANGE message to the RichTextBox, using the Device context of the Bitmap where the control is being printed.
More details available in the MSDN Docs: How to Print the Contents of Rich Edit Controls.
The ScrollableControlToBitmap() method takes only a ScrollableControl type as argument: you cannot pass a TextBox control, even if it uses ScrollBars.
▶ Set the fullSize argument to true or false to include all child controls inside a Container or just those that are visible. If set to true, the Container's ClientRectangle is expanded to include and print all its child Controls.
▶ Set the includeHidden argument to true or false to include or exclude the hidden control, if any.
Note: this code uses the Control.DeviceDpi property to evaluate the current Dpi of the container's Device Context. This property requires .Net Framework 4.7+. If this version is not available, you can remove:
bitmap.SetResolution(canvas.DeviceDpi, canvas.DeviceDpi);
or derive the value with other means. See GetDeviceCaps.
Possibly, update the Project's Framework version :)
// Prints the content of the current Form instance,
// include all child controls and also those that are not visible
var bitmap = ControlPrinter.ScrollableControlToBitmap(this, true, true);
// Prints the content of a ScrollableControl inside a Form
// include all child controls except those that are not visible
var bitmap = ControlPrinter.ScrollableControlToBitmap(this.panel1, true, false);
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
using System.Windows.Forms;
public class ControlPrinter
{
public static Bitmap ScrollableControlToBitmap(ScrollableControl canvas, bool fullSize, bool includeHidden)
{
canvas.AutoScrollPosition = new Point(0, 0);
if (includeHidden) {
canvas.SuspendLayout();
foreach (Control child in canvas.Controls) {
child.Visible = true;
}
canvas.ResumeLayout(true);
}
canvas.PerformLayout();
Size containerSize = canvas.DisplayRectangle.Size;
if (fullSize) {
containerSize.Width = Math.Max(containerSize.Width, canvas.ClientSize.Width);
containerSize.Height = Math.Max(containerSize.Height, canvas.ClientSize.Height);
}
else {
containerSize = canvas.ClientSize;;
}
var bitmap = new Bitmap(containerSize.Width, containerSize.Height, PixelFormat.Format32bppArgb);
bitmap.SetResolution(canvas.DeviceDpi, canvas.DeviceDpi);
var graphics = Graphics.FromImage(bitmap);
if (canvas.BackgroundImage != null) {
graphics.DrawImage(canvas.BackgroundImage, new Rectangle(Point.Empty, containerSize));
}
else {
graphics.Clear(canvas.BackColor);
}
var rtfPrinter = new RichEditPrinter(graphics);
try {
DrawNestedControls(canvas, canvas, new Rectangle(Point.Empty, containerSize), bitmap, rtfPrinter);
return bitmap;
}
finally {
rtfPrinter.Dispose();
graphics.Dispose();
}
}
private static void DrawNestedControls(Control outerContainer, Control parent, Rectangle parentBounds, Bitmap bitmap, RichEditPrinter rtfPrinter)
{
for (int i = parent.Controls.Count - 1; i >= 0; i--) {
var ctl = parent.Controls[i];
if (!ctl.Visible || (ctl.Width < 1 || ctl.Height < 1)) continue;
var clipBounds = Rectangle.Empty;
if (parent.Equals(outerContainer)) { clipBounds = ctl.Bounds; }
else {
Size scrContainerSize = parentBounds.Size;
if ((parent != ctl) && parent is ScrollableControl scrctl) {
if (scrctl.VerticalScroll.Visible) scrContainerSize.Width -= (SystemInformation.VerticalScrollBarWidth + 1);
if (scrctl.HorizontalScroll.Visible) scrContainerSize.Height -= (SystemInformation.HorizontalScrollBarHeight + 1);
}
clipBounds = Rectangle.Intersect(new Rectangle(Point.Empty, scrContainerSize), ctl.Bounds);
}
if (clipBounds.Width < 1 || clipBounds.Height < 1) continue;
var bounds = outerContainer.RectangleToClient(parent.RectangleToScreen(clipBounds));
if (ctl is RichTextBox rtb) {
rtfPrinter.DrawRtf(rtb.Rtf, outerContainer.Bounds, bounds, ctl.BackColor);
}
else {
ctl.DrawToBitmap(bitmap, bounds);
}
if (ctl.HasChildren) {
DrawNestedControls(outerContainer, ctl, clipBounds, bitmap, rtfPrinter);
}
}
}
internal class RichEditPrinter : IDisposable
{
Graphics dc = null;
RTBPrinter rtb = null;
public RichEditPrinter(Graphics graphics)
{
this.dc = graphics;
this.rtb = new RTBPrinter() { ScrollBars = RichTextBoxScrollBars.None };
}
public void DrawRtf(string rtf, Rectangle canvas, Rectangle layoutArea, Color color)
{
rtb.Rtf = rtf;
rtb.Draw(dc, canvas, layoutArea, color);
rtb.Clear();
}
public void Dispose() => this.rtb.Dispose();
private class RTBPrinter : RichTextBox
{
public void Draw(Graphics g, Rectangle hdcArea, Rectangle layoutArea, Color color)
{
using (var brush = new SolidBrush(color)) {
g.FillRectangle(brush, layoutArea);
};
IntPtr hdc = g.GetHdc();
var canvasAreaTwips = new RECT().ToInches(hdcArea);
var layoutAreaTwips = new RECT().ToInches(layoutArea);
var formatRange = new FORMATRANGE() {
charRange = new CHARRANGE() { cpMax = -1, cpMin = 0 },
hdc = hdc,
hdcTarget = hdc,
rect = layoutAreaTwips,
rectPage = canvasAreaTwips
};
IntPtr lParam = Marshal.AllocCoTaskMem(Marshal.SizeOf(formatRange));
Marshal.StructureToPtr(formatRange, lParam, false);
SendMessage(this.Handle, EM_FORMATRANGE, (IntPtr)1, lParam);
Marshal.FreeCoTaskMem(lParam);
g.ReleaseHdc(hdc);
}
[DllImport("User32.dll", CharSet = CharSet.Auto, SetLastError = true)]
internal static extern int SendMessage(IntPtr hWnd, int uMsg, IntPtr wParam, IntPtr lParam);
internal const int WM_USER = 0x0400;
// https://learn.microsoft.com/en-us/windows/win32/controls/em-formatrange
internal const int EM_FORMATRANGE = WM_USER + 57;
[StructLayout(LayoutKind.Sequential)]
internal struct RECT
{
public int Left;
public int Top;
public int Right;
public int Bottom;
public Rectangle ToRectangle() => Rectangle.FromLTRB(Left, Top, Right, Bottom);
public RECT ToInches(Rectangle rectangle)
{
float inch = 14.92f;
return new RECT() {
Left = (int)(rectangle.Left * inch),
Top = (int)(rectangle.Top * inch),
Right = (int)(rectangle.Right * inch),
Bottom = (int)(rectangle.Bottom * inch)
};
}
}
// https://learn.microsoft.com/en-us/windows/win32/api/richedit/ns-richedit-formatrange?
[StructLayout(LayoutKind.Sequential)]
internal struct FORMATRANGE
{
public IntPtr hdcTarget; // A HDC for the target device to format for
public IntPtr hdc; // A HDC for the device to render to, if EM_FORMATRANGE is being used to send the output to a device
public RECT rect; // The area within the rcPage rectangle to render to. Units are measured in twips.
public RECT rectPage; // The entire area of a page on the rendering device. Units are measured in twips.
public CHARRANGE charRange; // The range of characters to format (see CHARRANGE)
}
[StructLayout(LayoutKind.Sequential)]
internal struct CHARRANGE
{
public int cpMin; // First character of range (0 for start of doc)
public int cpMax; // Last character of range (-1 for end of doc)
}
}
}
}
This is how it works:
