BCB 中测量Richedit 的文本总行高

原创于 2019-04-15 08:25:03 发布 · 412 阅读

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#BCB 中测量Richedit 的文本总行高

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本文介绍了一种在BCB中使用EM_FORMATRANGE消息测量RichEdit控件中文本总行高的方法，通过获取设备上下文和设置FORMATRANGE结构来计算文本的实际高度，确保文字不会超出控件范围。

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BCB 中测量Richedit 的文本总行高

1，需要使用EM_FORMATRANGE 消息

2，实现的代码如下：

//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
: TForm(Owner)
{
}
//---------------------------------------------------------------------------

void __fastcall TForm1::Button1Click(TObject *Sender)
{
RichEdit1->Text = RichEdit1->Text.TrimRight();
int LogX,LogY;
HDC richdc = GetDC(RichEdit1->Handle);
LogX = GetDeviceCaps(richdc, LOGPIXELSX);
LogY = GetDeviceCaps(richdc, LOGPIXELSY);

FORMATRANGE formatrange = {0};
formatrange.hdc = richdc;
formatrange.hdcTarget = richdc;
formatrange.rc.left = 0;
formatrange.rc.top = 0;
formatrange.rc.right = RichEdit1->ClientWidth * 1440 / LogX;
formatrange.rc.bottom= Screen->Height* 1440 / LogY;
formatrange.rcPage = formatrange.rc;
formatrange.chrg.cpMin = 0;
formatrange.chrg.cpMax = -1;
RichEdit1->Perform(EM_FORMATRANGE,0,(long)&formatrange);
int totalHeight = formatrange.rc.bottom * LogY / 1440;
ShowMessage("文本总高度"+IntToStr(formatrange.rc.bottom * LogY / 1440));
RichEdit1->Perform(EM_FORMATRANGE,0,NULL);//free the cache

if (totalHeight > (RichEdit1->ClientHeight+3))
{
ShowMessage("文字超出范围！");
}

ReleaseDC(RichEdit1->Handle,richdc);
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button2Click(TObject *Sender)
{
RichEdit1->Font->Size++;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button3Click(TObject *Sender)
{
RichEdit1->Font->Size--;
}
//---------------------------------------------------------------------------