electron: [Bug]: Silent print was incorrect paper layout with webContents.print, but layout was correct when I use print dailog
Preflight Checklist
- I have read the Contributing Guidelines for this project.
- I agree to follow the Code of Conduct that this project adheres to.
- I have searched the issue tracker for a bug report that matches the one I want to file, without success.
Electron Version
25.3.1
What operating system are you using?
Windows
Operating System Version
Window 10 Pro Version 10.0.19045 Build 19045
What arch are you using?
x64
Last Known Working Electron version
25.3.1
Expected Behavior
This preview image I was use with dialog print. It shows exactly width and height that response from my URL. But I want to use with silent print.
Here is my code
ipcMain.handle('printComponent', async (_, url, printer_name, copies) => {
let win = new BrowserWindow({
show: false,
});
win.loadURL(url);
let _printer = printer_name;
let list = await win.webContents.getPrintersAsync();
let check = list.filter((r) => r.name === _printer);
if (check.length === 0) {
check = list.filter((r) => r.isDefault);
if (check.length > 0) {
_printer = check[0].name;
}
}
win.webContents.on('did-finish-load', () => {
const printOptions: WebContentsPrintOptions = {
deviceName: _printer,
silent: false,
margins: {
marginType: 'default',
},
landscape: false,
pagesPerSheet: 1,
collate: false,
copies,
};
win.webContents.print(printOptions, (success, failureReason) => {
console.log('Print Initiated in Main...');
if (!success) console.log(failureReason);
// win.close();
mainWindow?.focus();
});
});
});
Actual Behavior
This preview image I was use with silent print. It shows too small that response from my URL.
Here is my code
ipcMain.handle('printComponent', async (_, url, printer_name, copies) => {
let win = new BrowserWindow({
show: false,
});
win.loadURL(url);
let _printer = printer_name;
let list = await win.webContents.getPrintersAsync();
let check = list.filter((r) => r.name === _printer);
if (check.length === 0) {
check = list.filter((r) => r.isDefault);
if (check.length > 0) {
_printer = check[0].name;
}
}
win.webContents.on('did-finish-load', () => {
const printOptions: WebContentsPrintOptions = {
deviceName: _printer,
silent: true,
margins: {
marginType: 'default',
},
landscape: false,
pagesPerSheet: 1,
collate: false,
copies,
};
win.webContents.print(printOptions, (success, failureReason) => {
console.log('Print Initiated in Main...');
if (!success) console.log(failureReason);
// win.close();
mainWindow?.focus();
});
});
});
Testcase Gist URL
https://gist.github.com/053de2471f74277e60fb908aaa3685ff
Additional Information
No response
About this issue
- Original URL
- State: closed
- Created a year ago
- Reactions: 2
- Comments: 24
Setting the dpi:{ horizontal: 600, vertical: 600 } on the printOptions can workaround the issue.
@codebytere Do we have a timeline or a specific Electron version targeted for fixing this issue?
Having the same issue, I checked different versions today and can confirm the previous commenters. Silent printing by version (built with electron-packager v17.1.2 on MacOS and run on Win11 ARM in Parallels Desktop): 25.3.1-29.0.0-alpha.3 -> working but shrunk content on PDF 25.0.0-25.3.0 -> not working at all 24.8.8 -> working, correct size
Would be great to have this fixed, since 24.x is already end of life, but this forces me to stay on that version.
Thank you @Wexoo, I downgraded to 24.8.8 and it works perfectly
@codebytere any news on this? We’re stuck on 24.8.8 for quite a while now.
This issue is actually not fixed. The pdf is generated fine but the prints are not triggered with proper layout in silent mode. #41928 explains it.
I have the same issue also on Electron 28.x.
A thing I was able to discover is that, on Windows, pageSize is interpreted in the wrong way. To be able to print at full page I had to multiply by 10 the width and heights in microns, by means of the
pageSizeparameter. Instead of doingwebContents.print({silent: true, pageSize: "A4"}, callback), I invokedwebContents.print({silent: true, pageSize: {width: 2100000, height: 2970000}}, callback).By means of that, the content is still printed small, but moves to the top-left corner and the print is able to span to the full page. To get to a normal printing size I can set
dpi: {horizontal: 544, vertical: 544}or, alternatively, apply a CSSzoom: 750%on the page content, but that is not the right thing to do. Apart from the insane magnitude of the parameters, AFAIK increasing dpi settings so much could cause the printer to refuse the job, and using zoom breaks the ability to print the same page from a browser.I also verified that printing the page from Chrome or Chromium doesn’t present the same issue, but I struggle to find where the problem is in the Electron code base. It seems like, by doing a
silentprint request, some parameter doesn’t get initialized properly.FYI: On macOS everything is fine
My current workaround for windows is to utilize PrinterResolution class get the printer resolution and pass the dpi to the printer to print. I’ve noticed some printer drivers(Canon generic printer driver) could return dpi values <=0. You’d need to filter them out and only pass the positive one to webContent.print. Otherwise, you could encounter this issue.
It seems this error still exists until the latest version
27.0.2.The print function with option
{ silent: true }still works well toward version24.8.8, and started having errors on version25.0.0, this function starts working again in version25.3.1after this fix #39095 by @codebytere but make another error that causing prints to be very tiny.Has anyone solved this problem other than the trick above?
Everything work fine with “electron”: “^24.6.4” for layout paper printing but I want to upgrade with new version and now I stuck on that problem. Thanks for help