double-click on .ui file opens it in Qt Designer

python/pluginSrc/com/jetbrains/python/PythonFileTypeFactory.java

@@ -4,6 +4,7 @@ import com.intellij.openapi.fileTypes.FileTypeConsumer;
 import com.intellij.openapi.fileTypes.FileTypeFactory;
 import com.intellij.ultimate.PluginVerifier;
 import com.intellij.ultimate.UltimateVerifier;
+import com.jetbrains.pyqt.QtUIFileType;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
 
@@ -19,5 +20,6 @@ public class PythonFileTypeFactory extends FileTypeFactory {
 
   public void createFileTypes(@NonNls @NotNull final FileTypeConsumer consumer) {
     consumer.consume(PythonFileType.INSTANCE, "py;pyw;");
+    consumer.consume(QtUIFileType.INSTANCE, "ui");
   }
 }

python/src/com/jetbrains/pyqt/QtUIFileType.java

@@ -0,0 +1,107 @@
+package com.jetbrains.pyqt;
+
+import com.intellij.openapi.fileTypes.FileType;
+import com.intellij.openapi.fileTypes.INativeFileType;
+import com.intellij.openapi.module.Module;
+import com.intellij.openapi.module.ModuleUtil;
+import com.intellij.openapi.project.Project;
+import com.intellij.openapi.projectRoots.Sdk;
+import com.intellij.openapi.ui.Messages;
+import com.intellij.openapi.util.IconLoader;
+import com.intellij.openapi.util.SystemInfo;
+import com.intellij.openapi.vfs.VirtualFile;
+import com.intellij.psi.PsiDirectory;
+import com.intellij.psi.PsiElement;
+import com.jetbrains.python.psi.impl.PyQualifiedName;
+import com.jetbrains.python.psi.resolve.ResolveImportUtil;
+import com.jetbrains.python.sdk.PythonSdkType;
+import org.jetbrains.annotations.NotNull;
+
+import javax.swing.*;
+import java.io.IOException;
+import java.util.List;
+
+/**
+ * @author yole
+ */
+public class QtUIFileType implements FileType, INativeFileType {
+  public static QtUIFileType INSTANCE = new QtUIFileType();
+
+  private Icon myIcon = IconLoader.getIcon("/com/jetbrains/pyqt/uiForm.png");
+
+  @NotNull
+  @Override
+  public String getName() {
+    return "Qt UI file";
+  }
+
+  @NotNull
+  @Override
+  public String getDescription() {
+    return "Qt UI Designer form file";
+  }
+
+  @NotNull
+  @Override
+  public String getDefaultExtension() {
+    return "ui";
+  }
+
+  @Override
+  public Icon getIcon() {
+    return myIcon;
+  }
+
+  @Override
+  public boolean isBinary() {
+    return true;
+  }
+
+  @Override
+  public boolean isReadOnly() {
+    return false;
+  }
+
+  @Override
+  public String getCharset(@NotNull VirtualFile file, byte[] content) {
+    return null;
+  }
+
+  @Override
+  public boolean openFileInAssociatedApplication(Project project, VirtualFile file) {
+    if (SystemInfo.isWindows) {
+      Module module = ModuleUtil.findModuleForFile(file, project);
+      if (module == null) {
+        return false;
+      }
+      Sdk sdk = PythonSdkType.findPythonSdk(module);
+      if (sdk == null) {
+        return false;
+      }
+      List<PsiElement> qt4 =
+        ResolveImportUtil.resolveModulesInRootProvider(sdk.getRootProvider(), module, PyQualifiedName.fromComponents("PyQt4"));
+      for (PsiElement psiElement : qt4) {
+        if (psiElement instanceof PsiDirectory) {
+          VirtualFile designer = ((PsiDirectory)psiElement).getVirtualFile().findChild("designer.exe");
+          if (designer != null) {
+            try {
+              Runtime.getRuntime().exec(new String[] { designer.getPath(), file.getPath() } );
+            }
+            catch (IOException e) {
+              Messages.showErrorDialog(project, "Failed to run Qt Designer: " + e.getMessage(), "Error");
+            }
+            return true;
+          }
+        }
+      }
+
+   }
+    // TODO
+    return true;
+  }
+
+  @Override
+  public boolean useNativeIcon() {
+    return false;
+  }
+}