Cocoa: IME: implements a base NSTextInputClient for non-editable LCL CustomControl

implements a base NSTextInputClient for non-editable LCL CustomControl,
like Form, Grid, ListView, that are not system control and not FullEditControl.
1. when using IME in these controls, a temporary and one-time editor is shown at the bottom of the control, supporting IME such as Chinese.
2. refers to MacOS Finder, when using IME in the file list view, a small window will pop up at the bottom of the screen for input. the text can then be used for filename starting character match.
3. it is useful for implementing IME support for controls that do not have a text input window.

lcl/interfaces/cocoa/cocoaprivate.pas

@@ -203,6 +203,8 @@ type
 
     isdrawing   : integer;
     faileddraw  : Boolean;
+
+    _inIME: Boolean;
   public
     callback: ICommonCallback;
     auxMouseByParent: Boolean;
@@ -234,9 +236,19 @@ type
     function stringValue: NSString; override;
     procedure addSubView(aview: NSView); override;
 
-    // this is parts of
+  public
+    // NSTextInputClientProtocol related.
+    // implements a base NSTextInputClient for non-editable LCL CustomControl,
+    // like Form, Grid, ListView, that are not system control and not FullEditControl.
+    // 1. when using IME in these controls, a temporary and one-time editor is shown
+    //    at the bottom of the control, supporting IME such as Chinese.
+    // 2. refers to MacOS Finder, when using IME in the file list view,
+    //    a small window will pop up at the bottom of the screen for input.
+    //    the text can then be used for filename starting character match.
+    // 3. it is useful for implementing IME support for controls that do not
+    //    have a text input window.
+    procedure keyDown(theEvent: NSEvent); override;
     procedure insertText_replacementRange (aString: id; replacementRange: NSRange);
-    procedure doCommandBySelector (aSelector: SEL); override;
     procedure setMarkedText_selectedRange_replacementRange (aString: id; selectedRange: NSRange; replacementRange: NSRange);
     procedure unmarkText;
     function selectedRange: NSRange;
@@ -246,6 +258,7 @@ type
     function validAttributesForMarkedText: NSArray;
     function firstRectForCharacterRange_actualRange (aRange: NSRange; actualRange: NSRangePointer): NSRect;
     function characterIndexForPoint (aPoint: NSPoint): NSUInteger;
+    procedure doCommandBySelector (aSelector: SEL); override;
   end;
 
   { ICocoaIMEControl }
@@ -585,6 +598,14 @@ end;
 
 { TCocoaCustomControl }
 
+function getNSStringObject( const aString: id ) : NSString;
+begin
+  if aString.isKindOfClass( NSAttributedString.classClass ) then
+    Result:= NSAttributedString( aString ).string_
+  else
+    Result:= NSString( aString );
+end;
+
 procedure TCocoaCustomControl.setStringValue(avalue: NSString);
 begin
   if Assigned(fstr) then fstr.release;
@@ -617,25 +638,78 @@ begin
   end;
 end;
 
-procedure TCocoaCustomControl.insertText_replacementRange(aString: id;
+procedure TCocoaCustomControl.keyDown(theEvent: NSEvent);
-  replacementRange: NSRange);
+var
+  view: NSView;
+  isFirst: Boolean;
 begin
-  lclGetCallback.InputClientInsertText(NSStringToString(NSString(astring)));
+  isFirst:= not _inIME;
+  inputContext.handleEvent(theEvent);
+  if _inIME and isFirst then
+  begin
+    view:= self.window.fieldEditor_forObject(true, nil);
+    view.setFrameSize( NSMakeSize(self.frame.size.width,16) );
+    self.addSubView( view );
+  end
+  else if not _inIME then
+    inputContext.discardMarkedText;
 end;
 
-procedure TCocoaCustomControl.doCommandBySelector(aSelector: SEL);
+procedure TCocoaCustomControl.insertText_replacementRange(aString: id;
+  replacementRange: NSRange);
+var
+  textView: NSTextView;
+  nsText: NSString;
 begin
-  inherited doCommandBySelector(ASelector);
+  if not _inIME then exit;
+
+  textView:= NSTextView(self.window.fieldEditor_forObject(false,nil));
+  if Assigned(textView) then
+    textView.removeFromSuperview;
+
+  nsText:= getNSStringObject(aString);
+  lclGetCallback.InputClientInsertText(nsText.UTF8String);
+
+  unmarkText;
 end;
 
 procedure TCocoaCustomControl.setMarkedText_selectedRange_replacementRange(
   aString: id; selectedRange: NSRange; replacementRange: NSRange);
+var
+  textView: NSTextView;
+  nsText: NSString;
 begin
+  nsText:= getNSStringObject(aString);
+  if nsText.length > 0 then
+  begin
+    _inIME:= true;
+    textView:= NSTextView(self.window.fieldEditor_forObject(false,nil));
+    if Assigned(textView) then
+      textView.setMarkedText_selectedRange_replacementRange(aString,selectedRange,replacementRange);
+  end
+  else
+    unmarkText;
+end;
 
+function TCocoaCustomControl.hasMarkedText: LCLObjCBoolean;
+begin
+  Result := _inIME;
 end;
 
 procedure TCocoaCustomControl.unmarkText;
 begin
+  _inIME:= false;
+end;
+
+function TCocoaCustomControl.firstRectForCharacterRange_actualRange(
+  aRange: NSRange; actualRange: NSRangePointer): NSRect;
+var
+  point: NSPoint;
+  rect: NSRect;
+begin
+  point:= self.convertPoint_toView(NSZeroPoint, nil);
+  rect:= NSMakeRect(point.x, point.y, 0, 16);
+  Result:= self.window.convertRectToScreen(rect);
 end;
 
 function TCocoaCustomControl.selectedRange: NSRange;
@@ -648,11 +722,6 @@ begin
   Result := NSMakeRange(0,0);
 end;
 
-function TCocoaCustomControl.hasMarkedText: LCLObjCBoolean;
-begin
-  Result := false;
-end;
-
 function TCocoaCustomControl.attributedSubstringForProposedRange_actualRange(
   aRange: NSRange; actualRange: NSRangePointer): NSAttributedString;
 begin
@@ -664,18 +733,17 @@ begin
   Result := nil;
 end;
 
-function TCocoaCustomControl.firstRectForCharacterRange_actualRange(
-  aRange: NSRange; actualRange: NSRangePointer): NSRect;
-begin
-  Result := NSMakeRect(0,0,0,0);
-end;
-
 function TCocoaCustomControl.characterIndexForPoint(aPoint: NSPoint
   ): NSUInteger;
 begin
   Result := 0;
 end;
 
+procedure TCocoaCustomControl.doCommandBySelector(aSelector: SEL);
+begin
+  inherited doCommandBySelector(ASelector);
+end;
+
 procedure TCocoaCustomControl.dealloc;
 begin
   if Assigned(fstr) then fstr.release;
@@ -916,14 +984,6 @@ begin
   Result := not hasMarkedText();
 end;
 
-function getNSStringObject( const aString: id ) : NSString;
-begin
-  if aString.isKindOfClass( NSAttributedString.classClass ) then
-    Result:= NSAttributedString( aString ).string_
-  else
-    Result:= NSString( aString );
-end;
-
 function isIMEDuplicateCall( const newParams, currentParams: TCocoaIMEParameters ) : Boolean;
 begin
   Result:= false;