61 lines
2.2 KiB
Markdown
61 lines
2.2 KiB
Markdown
---
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layout: post
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title: Force "Print Document on" 11x17 Scaled
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tag:
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- technical
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---
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The Print Spooler API in Windows does not seem to have an option to force
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scaling to another paper size. Formerly, we would install the printer save the
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registry key in `HKCU\Printers\DevModePerUser`. Then, we could check the "Print
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Document On" option, apply the settings, and save the registry key again.
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Performing a diff of between the two sets of roughly 4000 hex values should give
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a subset of values that relate to "Print Document On." Finally, on installation
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we could read in the registry key after everything else had been setup, cycle
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through it changing the appropriate values based on our diff and then save the
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registry key. This stopped working.
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No new diffs could be collected that would update the scale to fit functionality
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that we needed. However, if the "Print Document On" option is manually set and
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the registry key is collected, that key can be used as the "diff" and the newly
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added printer would print scaled as desired. This has the unfortunate side
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effect of modifying all other settings on the printer including the name and
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color settings. As a work around, two different registry key "diffs" are used:
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one for color and one for black&white. Then, the first 30 hex characters can be
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chopped off in each key to make sure the printer name is not overwritten.
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```
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#include <windows.h>;
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int stf[][2] = {
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{8, 0},
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{10, 0},
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// and more keys
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};
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int setPrintDocumentOn(char *printerName) {
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HKEY hkey;
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// find the tree where the key we need to change resides
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RegOpenKey(HKEY_CURRENT_USER, "Printers\\DevModePerUser", &hkey);
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DWORD requiredSize = 0;
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DWORD dataType;
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// read in the key
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RegQueryValueEx(hkey, printerName, 0, &dataType, NULL, &requiredSize);
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char *DevModePerUserData = malloc(requiredSize);
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RegQueryValueEx(hkey, printerName, 0, &dataType, (BYTE *)DevModePerUserData, &requiredSize);
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// update the key
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int i = 0;
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for(i = 0; i < sizeof(stf) / 8; i++) {
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DevModePerUserData[stf[i][0]] = stf[i][1];
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}
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// and save our updates
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RegSetValueEx(hkey, printerName, 0, REG_BINARY, (BYTE *)DevModePerUserData, requiredSize);
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RegFlushKey(hkey);
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RegCloseKey(hkey);
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}
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```
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