Skip to content

Add configurable DPI for HTML image export #793

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
moises2657 wants to merge 2 commits into
base: master
Choose a base branch
from
Open

Add configurable DPI for HTML image export #793

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
b8af0da
Add configurable DPI support for HTML image export
Dec 4, 2025
7fc9d49
fix short implementation
Dec 4, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 10 additions & 0 deletions FastReport.Base/Export/Html/HTMLExport.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -168,6 +168,7 @@ public enum ExportType
private bool enableMargins = false;
private ExportType exportMode;
private bool enableVectorObjects = true;
private float imageDpi = 1.0f;

/// <summary>
/// hash:base64Image
Expand Down Expand Up @@ -444,6 +445,15 @@ public bool NotRotateLandscapePage
get { return notRotateLandscapePage; }
set { notRotateLandscapePage = value; }
}

/// <summary>
/// Gets or sets the DPI for exported images.
/// </summary>
public int ImageDpi
{
get { return (int)(96 * imageDpi); }
set { imageDpi = value / 96f; }
}

#endregion Public properties

Expand Down
26 changes: 14 additions & 12 deletions FastReport.Base/Export/Html/HTMLExportLayers.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -486,12 +486,14 @@ private string GetLayerPicture(ReportComponentBase obj, out float Width, out flo

int zoom = highQualitySVG ? 3 : 1;

using (System.Drawing.Image image =
using (Bitmap image =
new Bitmap(
(int)(Math.Abs(Math.Round(Width * Zoom * zoom))),
(int)(Math.Abs(Math.Round(Height * Zoom * zoom)))
(int)(Math.Abs(Math.Round(Width * Zoom * zoom * imageDpi))),
(int)(Math.Abs(Math.Round(Height * Zoom * zoom * imageDpi)))
))
{
float targetDpi = 96 * imageDpi;
image.SetResolution(targetDpi, targetDpi);
using (Graphics g = Graphics.FromImage(image))
{
var needClear = obj is TextObjectBase
Expand All @@ -511,27 +513,27 @@ private string GetLayerPicture(ReportComponentBase obj, out float Width, out flo

float dx = 0;
float dy = 0;
g.TranslateTransform((-Left - dx) * Zoom * zoom, (-Top - dy) * Zoom * zoom);
g.TranslateTransform((-Left - dx) * Zoom * zoom * imageDpi, (-Top - dy) * Zoom * zoom * imageDpi);

BorderLines oldLines = obj.Border.Lines;
obj.Border.Lines = BorderLines.None;
obj.Draw(new FRPaintEventArgs(g, Zoom * zoom, Zoom * zoom, Report.GraphicCache));
obj.Draw(new FRPaintEventArgs(g, Zoom * zoom * imageDpi, Zoom * zoom * imageDpi, Report.GraphicCache));
obj.Border.Lines = oldLines;
}

using (Bitmap b = new Bitmap(
(int)(Math.Abs(Math.Round(Width * Zoom))),
(int)(Math.Abs(Math.Round(Height * Zoom)))
(int)(Math.Abs(Math.Round(Width * Zoom * imageDpi))),
(int)(Math.Abs(Math.Round(Height * Zoom * imageDpi)))
))
{
using (Graphics gr = Graphics.FromImage(b))
{
gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
gr.DrawImage(image, 0, 0, (int)Math.Abs(Width) * Zoom, (int)Math.Abs(Height) * Zoom);
gr.DrawImage(image, 0, 0, (int)Math.Abs(Width) * Zoom * imageDpi, (int)Math.Abs(Height) * Zoom * imageDpi);
}

if (FPictureFormat == System.Drawing.Imaging.ImageFormat.Jpeg)
ExportUtils.SaveJpeg(b, PictureStream, 95);
ExportUtils.SaveJpeg(b, PictureStream, 100);
else
b.Save(PictureStream, FPictureFormat);
}
Expand Down Expand Up @@ -595,7 +597,7 @@ private void LayerPicture(FastString Page, ReportComponentBase obj, FastString t
(obj as TextObject).Text = old_text;

FastString picStyleBuilder = new FastString("background: url('")
.Append(pic).Append("') no-repeat !important;-webkit-print-color-adjust:exact;");
.Append(pic).Append("') no-repeat !important;background-size:contain !important;-webkit-print-color-adjust:exact;");

string style = GetStyle(obj, picStyleBuilder.ToString());

Expand All @@ -619,7 +621,7 @@ private void LayerShape(FastString Page, ShapeObject obj, FastString text)

addstyle.Append("position:absolute;");

addstyle.Append("background: url('" + GetLayerPicture(obj, out Width, out Height) + "');no-repeat !important;-webkit-print-color-adjust:exact;");
addstyle.Append("background: url('" + GetLayerPicture(obj, out Width, out Height) + "');no-repeat !important;background-size:contain !important;-webkit-print-color-adjust:exact;");

float x = obj.Width > 0 ? obj.AbsLeft : (obj.AbsLeft + obj.Width);
float y = obj.Height > 0 ? hPos + obj.AbsTop : (hPos + obj.AbsTop + obj.Height);
Expand Down Expand Up @@ -816,7 +818,7 @@ private void ExportHTMLPageLayeredBegin(HTMLData d)
backPage.Width = reportPage.Width;
string pic = GetLayerPicture(backPage, out float Width, out float Height);
htmlPage.Append("background: url('")
.Append(pic).Append("') no-repeat !important;-webkit-print-color-adjust:exact;");
.Append(pic).Append("') no-repeat !important;background-size:contain !important;-webkit-print-color-adjust:exact;");
}
}
htmlPage.Append("\">");
Expand Down