夸父

下面例子实现ms word风格的段落整体对齐功能，当在段落头按下tab键时，段落整体向右收缩，当按下backspace键时，段落整体向左收缩

//定义向右收缩样式

ChangeFirstIndentConversion(Sender: TCustomRichViewEdit;

  StyleNo, UserData: Integer; AppliedToText: Boolean;

  var NewStyleNo: Integer);

var ParaStyle: TParaInfo;

begin

  ParaStyle := TParaInfo.Create(nil);

  ParaStyle.Assign(Sender.Style.ParaStyles[StyleNo]);

  ParaStyle.FirstIndent := UserData;

  ParaStyle.Standard := False;

  NewStyleNo := Sender.Style.ParaStyles.FindSuchStyle(StyleNo, ParaStyle,

    RVAllParaInfoProperties);

  if NewStyleNo<0 then begin

    Sender.Style.ParaStyles.Add.Assign(ParaStyle);

    NewStyleNo := Sender.Style.ParaStyles.Count-1;

  end;

  ParaStyle.Free;

end;

//定义向左收缩样式

ChangeLeftIndentConversion(Sender: TCustomRichViewEdit;

  StyleNo, UserData: Integer; AppliedToText: Boolean;

  var NewStyleNo: Integer);

var ParaStyle: TParaInfo;

begin

  ParaStyle := TParaInfo.Create(nil);

  ParaStyle.Assign(Sender.Style.ParaStyles[StyleNo]);

  ParaStyle.LeftIndent := UserData;

  if ParaStyle.LeftIndent=0 then

    ParaStyle.FirstIndent := 0;

  ParaStyle.Standard := False;

  NewStyleNo := Sender.Style.ParaStyles.FindSuchStyle(StyleNo, ParaStyle,

    RVAllParaInfoProperties);

  if NewStyleNo<0 then begin

    Sender.Style.ParaStyles.Add.Assign(ParaStyle);

    NewStyleNo := Sender.Style.ParaStyles.Count-1;

  end;

  ParaStyle.Free;

end;

//实现过程

function ChangeIndent(rve: TCustomRichViewEdit;

  Step, Max: Integer): Boolean;

var OldParaStyleConversion: TRVStyleConversionEvent;

    FirstIndent, LeftIndent: Integer;

    ListNo, ListLevel, StartFrom: Integer;

    Reset: Boolean; 

begin

  Result := False;

  OldParaStyleConversion := rve.OnParaStyleConversion;

  try

    rve := rve.TopLevelEditor; 

    if rve.SelectionExists then

      exit;

    if (Step>0) and (rve.OffsetInCurItem<=rve.GetOffsBeforeItem(rve.CurItemNo)) and

       (rve.CurItemNo>0) and (rve.GetItemStyle(rve.CurItemNo-1)=rvsListMarker) then begin

       // 改变段落位置

       rve.GetListMarkerInfo(rve.CurItemNo, ListNo, ListLevel, StartFrom, Reset);

       if (ListNo>=0) and (ListNo<rve.Style.ListStyles.Count) and

          (ListLevel+1<rve.Style.ListStyles[ListNo].Levels.Count) then begin

         rve.ChangeListLevels(+1);

         Result := True;

       end;

       exit;

    end;

 

    if (rve.OffsetInCurItem>rve.GetOffsBeforeItem(rve.CurItemNo)) or

      not rve.IsParaStart(rve.CurItemNo) then

      exit; // 不在段落开头不作处理

    if (rve.OffsetInCurItem>=rve.GetOffsAfterItem(rve.CurItemNo)) and

      ((rve.CurItemNo=rve.ItemCount-1) or rve.IsParaStart(rve.CurItemNo)) then

      exit; // 内容为空，不作处理

    FirstIndent := rve.Style.ParaStyles[rve.GetItemPara(rve.CurItemNo)].FirstIndent;

    LeftIndent  := rve.Style.ParaStyles[rve.GetItemPara(rve.CurItemNo)].LeftIndent;

    if Step>0 then begin

      if FirstIndent=0 then begin

        rve.OnParaStyleConversion := ChangeFirstIndentConversion;

        rve.ApplyParaStyleConversion(Step);

        Result := True;

        end

      else begin

        inc(LeftIndent, Step);

        if LeftIndent>Max then

          LeftIndent := Max;

        if LeftIndent>rve.Style.ParaStyles[rve.GetItemPara(rve.CurItemNo)].LeftIndent then begin

          rve.OnParaStyleConversion := ChangeLeftIndentConversion;

          rve.ApplyParaStyleConversion(LeftIndent);

          Result := True;

        end;

      end

      end

    else begin

     if FirstIndent>0 then begin 

        rve.OnParaStyleConversion := ChangeFirstIndentConversion;

        rve.ApplyParaStyleConversion(0);

        Result := True;

        end

      else begin

        inc(LeftIndent, Step);

        if LeftIndent<0 then

          LeftIndent := 0;

        if (LeftIndent

           (FirstIndent<>0) then begin

          rve.OnParaStyleConversion := ChangeLeftIndentConversion;

          rve.ApplyParaStyleConversion(LeftIndent);

          Result := True;

        end;

      end;

    end;

  finally

    rve.OnParaStyleConversion := OldParaStyleConversion;

  end;

end;

//最后在keypress下面处理

var step: Integer;

  begin

  if Key=#9 then begin

    step := 48;

    if GetAsyncKeyState(VK_SHIFT)and$8000<>0 then

      step := -step;

    if ChangeIndent(TCustomRichViewEdit(Sender), step, 480) then

      Key := #0;

  end;

  end;