好的，我不确定我的解决方案是否真的“不错”，但它似乎对我有用：我刚刚创建了QPlainTextEdit_My继承自的新类，QPlainTextEdit并添加了新方法appendPlainTextNoNL()、、、。appendHtmlNoNL()insertNL()
请注意：仔细阅读有关参数的评论check_nl，check_br这很重要！我花了几个小时来弄清楚为什么当我在没有新段落的情况下附加文本时我的小部件会这么慢。
/******************************************************************************************
* INCLUDED FILES
*****************************************************************************************/
#include "qplaintextedit_my.h"
#include <QScrollBar>
#include <QTextCursor>
#include <QStringList>
#include <QRegExp>
/******************************************************************************************
* CONSTRUCTOR, DESTRUCTOR
*****************************************************************************************/
QPlainTextEdit_My::QPlainTextEdit_My(QWidget *parent) :
QPlainTextEdit(parent)
{
}
QPlainTextEdit_My::QPlainTextEdit_My(const QString &text, QWidget *parent) :
QPlainTextEdit(text, parent)
{
}
/******************************************************************************************
* METHODS
*****************************************************************************************/
/* private */
/* protected */
/* public */
/**
* append html without adding new line (new paragraph)
*
* @param html html text to append
* @param check_nl if true, then text will be splitted by \n char,
* and each substring will be added as separate QTextBlock.
* NOTE: this important: if you set this to false,
* then you should append new blocks manually (say, by calling appendNL() )
* because one huge block will significantly slow down your widget.
*/
void QPlainTextEdit_My::appendPlainTextNoNL(const QString &text, bool check_nl)
{
QScrollBar *p_scroll_bar = this->verticalScrollBar();
bool bool_at_bottom = (p_scroll_bar->value() == p_scroll_bar->maximum());
if (!check_nl){
QTextCursor text_cursor = QTextCursor(this->document());
text_cursor.movePosition(QTextCursor::End);
text_cursor.insertText(text);
} else {
QTextCursor text_cursor = QTextCursor(this->document());
text_cursor.beginEditBlock();
text_cursor.movePosition(QTextCursor::End);
QStringList string_list = text.split('\n');
for (int i = 0; i < string_list.size(); i++){
text_cursor.insertText(string_list.at(i));
if ((i + 1) < string_list.size()){
text_cursor.insertBlock();
}
}
text_cursor.endEditBlock();
}
if (bool_at_bottom){
p_scroll_bar->setValue(p_scroll_bar->maximum());
}
}
/**
* append html without adding new line (new paragraph)
*
* @param html html text to append
* @param check_br if true, then text will be splitted by "<br>" tag,
* and each substring will be added as separate QTextBlock.
* NOTE: this important: if you set this to false,
* then you should append new blocks manually (say, by calling appendNL() )
* because one huge block will significantly slow down your widget.
*/
void QPlainTextEdit_My::appendHtmlNoNL(const QString &html, bool check_br)
{
QScrollBar *p_scroll_bar = this->verticalScrollBar();
bool bool_at_bottom = (p_scroll_bar->value() == p_scroll_bar->maximum());
if (!check_br){
QTextCursor text_cursor = QTextCursor(this->document());
text_cursor.movePosition(QTextCursor::End);
text_cursor.insertHtml(html);
} else {
QTextCursor text_cursor = QTextCursor(this->document());
text_cursor.beginEditBlock();
text_cursor.movePosition(QTextCursor::End);
QStringList string_list = html.split(QRegExp("\\<br\\s*\\/?\\>", Qt::CaseInsensitive));
for (int i = 0; i < string_list.size(); i++){
text_cursor.insertHtml( string_list.at(i) );
if ((i + 1) < string_list.size()){
text_cursor.insertBlock();
}
}
text_cursor.endEditBlock();
}
if (bool_at_bottom){
p_scroll_bar->setValue(p_scroll_bar->maximum());
}
}
/**
* Just insert new QTextBlock to the text.
* (in fact, adds new paragraph)
*/
void QPlainTextEdit_My::insertNL()
{
QScrollBar *p_scroll_bar = this->verticalScrollBar();
bool bool_at_bottom = (p_scroll_bar->value() == p_scroll_bar->maximum());
QTextCursor text_cursor = QTextCursor(this->document());
text_cursor.movePosition(QTextCursor::End);
text_cursor.insertBlock();
if (bool_at_bottom){
p_scroll_bar->setValue(p_scroll_bar->maximum());
}
}
我很困惑，因为在原始代码中有更复杂的计算atBottom：
const bool atBottom = q->isVisible()
&& (control->blockBoundingRect(document->lastBlock()).bottom() - verticalOffset()
<= viewport->rect().bottom());
和needScroll：
if (atBottom) {
const bool needScroll = !centerOnScroll
|| control->blockBoundingRect(document->lastBlock()).bottom() - verticalOffset()
> viewport->rect().bottom();
if (needScroll)
vbar->setValue(vbar->maximum());
}
但我的简单解决方案似乎也有效。