rich copy: make text pasted in target application have same size as original text in IDEA editor

platform/lang-impl/src/com/intellij/openapi/editor/richcopy/TextWithMarkupProcessor.java

@@ -20,6 +20,7 @@ import com.intellij.codeInsight.daemon.impl.HighlightInfoType;
 import com.intellij.codeInsight.editorActions.CopyPastePostProcessor;
 import com.intellij.codeInsight.editorActions.CopyPastePreProcessor;
 import com.intellij.ide.highlighter.HighlighterFactory;
+import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.editor.*;
 import com.intellij.openapi.editor.colors.EditorColorsScheme;
@@ -45,6 +46,7 @@ import com.intellij.openapi.editor.richcopy.view.RtfTransferableData;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.util.Pair;
 import com.intellij.openapi.util.Ref;
+import com.intellij.openapi.util.SystemInfo;
 import com.intellij.openapi.util.registry.Registry;
 import com.intellij.psi.PsiFile;
 import com.intellij.psi.TokenType;
@@ -271,7 +273,17 @@ public class TextWithMarkupProcessor extends CopyPastePostProcessor<RawTextWithM
       myText = charSequence;
       myDefaultForeground = scheme.getDefaultForeground();
       myDefaultBackground = scheme.getDefaultBackground();
-      builder = new SyntaxInfo.Builder(myDefaultForeground, myDefaultBackground, scheme.getEditorFontSize());
+
+      // Java assumes screen resolution of 72dpi when calculating font size in pixels. External applications are supposedly using correct
+      // resolution, so we need to adjust font size for copied text to look the same in them.
+      // (See https://docs.oracle.com/javase/7/docs/webnotes/tsg/TSG-Desktop/html/java2d.html#gdlwn)
+      // Java on Mac is not affected by this issue.
+      int javaFontSize = scheme.getEditorFontSize();
+      float fontSize = SystemInfo.isMac || ApplicationManager.getApplication().isHeadlessEnvironment() ? 
+                       javaFontSize : 
+                       javaFontSize * 72f / Toolkit.getDefaultToolkit().getScreenResolution();
+      
+      builder = new SyntaxInfo.Builder(myDefaultForeground, myDefaultBackground, fontSize);
       myIndentSymbolsToStrip = indentSymbolsToStrip;
     }
 

platform/lang-impl/src/com/intellij/openapi/editor/richcopy/model/SyntaxInfo.java

@@ -34,13 +34,13 @@ public class SyntaxInfo {
 
   private final int myDefaultForeground;
   private final int myDefaultBackground;
-  private final int myFontSize;
+  private final float myFontSize;
 
   private SyntaxInfo(int outputInfoCount,
                      byte[] outputInfosSerialized,
                     int defaultForeground,
                     int defaultBackground,
-                    int fontSize,
+                    float fontSize,
                     @NotNull FontNameRegistry fontNameRegistry,
                     @NotNull ColorRegistry colorRegistry)
   {
@@ -71,7 +71,7 @@ public class SyntaxInfo {
     return myDefaultBackground;
   }
 
-  public int getFontSize() {
+  public float getFontSize() {
     return myFontSize;
   }
 
@@ -146,12 +146,12 @@ public class SyntaxInfo {
     private final FontNameRegistry myFontNameRegistry = new FontNameRegistry();
     private final int myDefaultForeground;
     private final int myDefaultBackground;
-    private final int myFontSize;
+    private final float myFontSize;
     private final ByteArrayOutputStream myStream = new ByteArrayOutputStream();
     private final OutputInfoSerializer.OutputStream myOutputInfoStream;
     private int myOutputInfoCount;
 
-    public Builder(Color defaultForeground, Color defaultBackground, int fontSize) {
+    public Builder(Color defaultForeground, Color defaultBackground, float fontSize) {
       myDefaultForeground = myColorRegistry.getId(defaultForeground);
       myDefaultBackground = myColorRegistry.getId(defaultBackground);
       myFontSize = fontSize;

platform/lang-impl/src/com/intellij/openapi/editor/richcopy/view/HtmlTransferableData.java

@@ -83,7 +83,7 @@ public class HtmlTransferableData extends AbstractSyntaxAwareReaderTransferableD
       else {
         myFontFamily = myDefaultFontFamily = -1;
       }
-      myResultBuffer.append("font-size:").append(mySyntaxInfo.getFontSize()).append("pt;\">");
+      myResultBuffer.append(String.format("font-size:%.1fpt;\">", mySyntaxInfo.getFontSize()));
 
       mySyntaxInfo.processOutputInfo(this);
 

platform/lang-impl/src/com/intellij/openapi/editor/richcopy/view/RtfTransferableData.java

@@ -77,8 +77,8 @@ public class RtfTransferableData extends AbstractSyntaxAwareInputStreamTransfera
     return "US-ASCII";
   }
 
-  private static void addFontSize(StringBuilder buffer, int fontSize) {
-    buffer.append("\\fs").append(fontSize * 2);
+  private static void addFontSize(StringBuilder buffer, float fontSize) {
+    buffer.append("\\fs").append(Math.round(fontSize * 2));
   }
 
   private static class MyVisitor implements MarkupHandler {
@@ -88,7 +88,7 @@ public class RtfTransferableData extends AbstractSyntaxAwareInputStreamTransfera
     private final int myMaxLength;
 
     private final int myDefaultBackgroundId;
-    private final int myFontSize;
+    private final float myFontSize;
     private int myForegroundId = -1;
     private int myFontNameId   = -1;
     private int myFontStyle    = -1;

platform/platform-tests/testSrc/com/intellij/openapi/editor/richcopy/SyntaxInfoConstructionTest.java

@@ -305,7 +305,7 @@ public class SyntaxInfoConstructionTest extends LightPlatformCodeInsightFixtureT
         final ColorRegistry colorRegistry = syntaxInfo.getColorRegistry();
         assertEquals(JBColor.BLACK, colorRegistry.dataById(syntaxInfo.getDefaultForeground()));
         assertEquals(JBColor.WHITE, colorRegistry.dataById(syntaxInfo.getDefaultBackground()));
-        assertEquals(getFontSize(), syntaxInfo.getFontSize());
+        assertEquals((float)getFontSize(), syntaxInfo.getFontSize(), 0.01f);
         syntaxInfo.processOutputInfo(new MarkupHandler() {
           @Override
           public void handleText(int startOffset, int endOffset) throws Exception {