Chinese character doesn’t display correctlly in qml when the content to display is vast

[yaotong]

Hi everyone
my Qt Version is Qt5.1,cross compiled for imx6s,HMI is using qtquick2.0.
my developing board's ram is less then 512M,at beginning,everything of chinese display is ok,
but when we have a mass of chinese to display(like news),
then characters of chinese are Blurred,like the font pixels are corrupted,but english character is not affected.

who can give any suggestions of what is the problem or which point may affect this.
some remarks:
1.OS environment is Linux.
2.font rending is using freetype.
3.soft environment is muilti-process and muil-thread.
thansk very much.

[jiangcaiyang]

这个是嵌入式的编译吗？如果显示的文字较多，可否使用懒载入策略，即只载入需要的部分即可。
另外可能configure阶段也有问题。能贴出configure参数吗？

[yaotong]

是为嵌入式Linux编译的版本。
能详细说一下你所说的载入策略吗？具体怎么使用？
我的configure参数就是再普通不过的参数了，没有什么特殊的配置。

[jiangcaiyang]

虽然我没有做过嵌入式，但是我知道一点，如果内存占用比较大的话，会造成溢出。
你这种情况，嵌入式系统没有显卡吧？那么系统显示相关的部分被文字溢出的那部分影响到了。我曾经搞过CUDA，有一次就不小心访问了不该访问的显存，造成了电脑文字渲染变花。
如果能做到懒加载策略，你的问题应该不会存在了。

[yaotong]

首先谢谢你的回复。
我使用的是freescale 的imx6s，没有显卡的。
你所指的懒加载是怎么个策略？是指文字显示还是字库的加载？

[jiangcaiyang]

懒加载策略参见手机微博客户端，大概就是这个意思。或者说只要不被显示的部分就在内存中销毁。

[yaotong]

问题大体上可以定位了，和内存泄露或溢出没有关系，是QML的gridview通过model现实数据时就会出现花屏的。
具体QML的bug还是使用不当还没有查清楚。

[yaotong]

!https://bugreports.qt-project.org/secure/thumbnail/37090/_thumb_37090.png(blurred text)!
哪位高人给看看是否是代码存在缺陷而导致花屏还是QML本身的缺陷。
"https://bugreports.qt-project.org/secure/attachment/37048/GridView.tar.bz2":https://bugreports.qt-project.org/secure/attachment/37048/GridView.tar.bz2
代码如下：
@//Gridview.pro

Add more folders to ship with the application, here

Additional import path used to resolve QML modules in Creator's code model

QT += qml quick

QML_IMPORT_PATH = ./

The .cpp file which was generated for your project. Feel free to hack it.

SOURCES += main.cpp
listmodel.cpp

Installation path

target.path =

HEADERS +=
listmodel.h

OTHER_FILES +=
gridview.qml
database.txt

//main.cpp
#include <QGuiApplication>
#include <qqmlengine.h>
#include <qqmlcontext.h>
#include <qqml.h>
#include <QtQuick/qquickitem.h>
#include <QtQuick/qquickview.h>

#include <QTextCodec>

#include "listmodel.h"

int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);

//QTextCodec *codec=QTextCodec::codecForName("UTF-8");
//QTextCodec::setCodecForLocale(codec);

ListModel model(NULL,3);

QQuickView view;
//view.setResizeMode(QQuickView::SizeRootObjectToView);
view.setGeometry(100,100,1000,400);
view.setMaximumSize(view.size());
view.setMinimumSize(view.size());
//view.setSurfaceType(QSurface::OpenGLSurface);
//view.setPersistentOpenGLContext(false);

QQmlContext *ctxt = view.rootContext();
ctxt->setContextProperty("DataModel", &model);

view.setSource(QUrl("./gridview.qml"));
view.show();

return app.exec();

}

//listmodel.h
#ifndef LISTMODEL_H
#define LISTMODEL_H

#include <QAbstractListModel>
#include <QStringList>

#include <QDebug>

#define ENCODE_NAME "UTF-8"

enum DATA_TYPE
{
ITEM_BINARY,
ITEM_STRING
};

class CListItem
{
public:
CListItem();
~CListItem();

void pushData(DATA_TYPE type, const void * data, int size);
void setData(int index, DATA_TYPE type, void * data, int size);
QString getData(int index);

protected:
QList<QString> item;
};

class ListModel: public QAbstractListModel
{
Q_OBJECT
Q_PROPERTY(int currentIndex READ getCurrentIndex WRITE setCurrentIndex)
Q_PROPERTY(int showNum READ getShowNum)

public:
ListModel(QObject *parent,int colcount);
~ListModel();

enum ListModelRoles {
    UserDataRole = Qt::UserRole + 1,
};

void addItem(CListItem * item);
void removeItem(int index);
void modifyItem(int row, int col, DATA_TYPE type, void * data, int size);

int rowCount(const QModelIndex & parent = QModelIndex()) const;
QVariant data(const QModelIndex & index, int role = Qt::DisplayRole) const;

QHash<int, QByteArray> roleNames() const;

int getCurrentIndex();
void setCurrentIndex(int index);


int getTotalRecNum();
void showContactData(int m_Booknum, int index);

int getShowNum();

signals:
void indexChanged();

protected:
QList<CListItem *> items;
QHash<int, QByteArray> roles;
int colCount;
int currIndex;
};

#endif // LISTMODEL_H
@

[yaotong]

@//listmodel.cpp
#include <QFile>
#include <QTextStream>
#include <QTextCodec>
#include <QStringList>

#include "listmodel.h"

CListItem::CListItem()
{
//do nothing
}

CListItem::~CListItem()
{
item.clear();
}

void CListItem::pushData(DATA_TYPE type, const void * data, int size)
{
if(type == ITEM_BINARY)
{
//do nothing
}
else
{
item.append(QString(QByteArray((const char *)data,size)));
}
}

void CListItem::setData(int index, DATA_TYPE type, void * data, int size)
{
Q_UNUSED(index);
Q_UNUSED(data);
Q_UNUSED(size);

if(type == ITEM_BINARY)
{
    //do nothing
}
else
{
    //do nothing
}

}

QString CListItem::getData(int index)
{
return item.at(index);
}

ListModel::ListModel(QObject *parent,int colcount): QAbstractListModel(parent)
{
int index = 0;
colCount = colcount;
QString strTmp=QString();
for(index = 0; index < colCount; index++)
{
strTmp.clear();
strTmp = strTmp.sprintf("col%d",index);
roles[UserDataRole + index] = strTmp.toLocal8Bit();
}

currIndex = 1;
showContactData(getShowNum(),currIndex);

}

ListModel::~ListModel()
{
//do nothing
// for(int index=0;index<items.count()-1;index++)
// {
// delete items.at(index);
// }
// beginRemoveRows(QModelIndex(),0,rowCount());
// endRemoveRows();
// items.clear();
// resetInternalData();
}

void ListModel::addItem(CListItem * item)
{
beginInsertRows(QModelIndex(), rowCount(), rowCount());
items.append(item);
endInsertRows();
}

void ListModel::removeItem(int index)
{
Q_UNUSED(index);
//do nothing
}

void ListModel::modifyItem(int row, int col, DATA_TYPE type, void * data, int size)
{
Q_UNUSED(row);
Q_UNUSED(col);
Q_UNUSED(type);
Q_UNUSED(data);
Q_UNUSED(size);
//do nothing
}

int ListModel::rowCount(const QModelIndex & parent) const
{
Q_UNUSED(parent);
return items.count();
}

QVariant ListModel::data(const QModelIndex & index, int role) const
{
if (index.row() < 0 || index.row() >= rowCount())
{
return QVariant();
}

CListItem *item = items.at(index.row());
if (role >= UserDataRole)
{
    return QVariant(item->getData(role-UserDataRole));
}
else
{
    return QVariant();
}

}

QHash<int, QByteArray> ListModel::roleNames() const
{
return roles;
}

int ListModel::getCurrentIndex()
{
return this->currIndex;
}

void ListModel::setCurrentIndex(int index)
{
this->currIndex = index;
//emit indexChanged();
showContactData(getShowNum(),this->currIndex);
}

#define DATABASE_NAME "./database.txt"
int ListModel::getTotalRecNum()
{
int listnum;
QTextCodec *codec=QTextCodec::codecForName(ENCODE_NAME);
QFile file(DATABASE_NAME);
file.open(QIODevice::ReadOnly);
QTextStream reader(&file);
reader.setCodec(codec);
listnum=1;
while(!reader.readLine().isNull()) {listnum++;}
file.close();
return listnum;
}

//get record data from local file
//local file is encoded by utf-8
//m_Booknum:fetch count each time
//index:the range of index to fetch,for example,1-10,11-20,21-30
void ListModel::showContactData(int m_Booknum, int index)
{
// //beginResetModel();
// for(int index=0;index<items.count()-1;index++)
// {
// delete items.at(index);
// }
// beginRemoveRows(QModelIndex(),0,rowCount());
// endRemoveRows();
// items.clear();
// resetInternalData();
// //endResetModel();

QTextCodec *codec=QTextCodec::codecForName(ENCODE_NAME);
QFile file(DATABASE_NAME);
file.open(QIODevice::ReadOnly);
QTextStream reader(&file);
reader.setCodec(codec);
QString Line="";
bool bln=true;
while(!Line.isNull())
{
    Line=reader.readLine();
    if(Line.split(":").at(0).toLong(&bln) == index)
    {
        break;
    }
}


int myIndex =0;
for(myIndex=0;myIndex < m_Booknum;myIndex++)
{
    if(!Line.isNull())
    {
        CListItem *item = new CListItem();
        QList<QString> spList;
        spList = Line.split(":");
        item->pushData(ITEM_STRING,spList.at(1).toUtf8().data(),spList.at(1).toUtf8().length());
        item->pushData(ITEM_STRING,spList.at(2).toUtf8().data(),spList.at(2).toUtf8().length());
        item->pushData(ITEM_STRING,spList.at(3).toUtf8().data(),spList.at(3).toUtf8().length());
        addItem(item);
        Line=reader.readLine();
        qDebug() << "fetching data... ..." << myIndex+1;
    }
    else
    {
        break;
    }
}
file.close();

}

int ListModel::getShowNum()
{
return 20;
}

@

[yaotong]

@//gridview.qml
import QtQuick 2.0

Rectangle {
width: 1000; height: 400
color: "white"

//DataModel.showNum:default is 20
property int contactIndex: DataModel.showNum
property int maxPosX:0
property int fontsize:30
property string fontname: "宋体"
property string fontcolor: "white"

Component {
    id: modelDelegate

    Item {
        width: 200; height: 200
        Rectangle {
            x:10
            y:10
            width: 180; height: 180
            radius:15
            color:"#282828"

            Text {
                id:firstName
                y: 20;
                font.pixelSize : fontsize
                //font.family: fontname
                color:fontcolor
                anchors { horizontalCenter: parent.horizontalCenter }
                //renderType:Text.QtRendering
                //textFormat:Text.PlainText
                antialiasing:true
                text: col0
            }

            Text {
                id:lastName
                y: 60;
                font.pixelSize : fontsize
                font.family: fontname
                color:fontcolor
                anchors { horizontalCenter: parent.horizontalCenter  }
                //renderType:Text.NativeRendering
                //textFormat:Text.PlainText
                antialiasing:true
                font.capitalization:Font.AllLowercase
                text: col1
            }

            Text {
                id:contactNumber
                y: 120;
                font.pixelSize : 20
                font.family: fontname
                color:fontcolor
                anchors { horizontalCenter: parent.horizontalCenter  }
                text: col2
            }
        }
    }
}

Component {
    id: itemHighlight
    Rectangle { width: 180; height: 180; color: "red" }
}




GridView {
    anchors.fill: parent
    cellWidth: 200; cellHeight: 200
    highlight: itemHighlight
    focus: true
    flow:GridView.TopToBottom
    layoutDirection:Qt.LeftToRight

    model: DataModel
    delegate: modelDelegate

    //currentIndex:-1
    //cacheBuffer:500

    populate: Transition {
            NumberAnimation { properties: "x,y"; duration: 800 }
    }

    snapMode:GridView.SnapToRow

    onFlickEnded:
    {
        //if flick to left then fetch data
        if (contentX >= maxPosX)
        {
            maxPosX = contentX
            //DataModel.showNum:default is 20
            contactIndex = contactIndex + DataModel.showNum
            DataModel.currentIndex = contactIndex
        }
    }
}

}
@

[yaotong]

//database.txt
1 :应:用网:268272005179
2 :易:首页:120833637064
3 :欢:迎您:414447531903
4 :安:全退:173395320420
5 :出:微博:125426977250
6 :邮:箱支:102885585596
7 :付:人民:751030750109
8 :网:海南:192095842147
9 :视:窗月:176418287893
10 :日:电近:160073325236
11 :日:海南:373290680377
12 :省:第二:184158916726
13 :中:级人:152332696404
14 :民:法院:110102756857
15 :就:备受:651770108192
16 :媒:体关:321272084251
17 :注:的成:195969428173
18 :都:女子:781391289232
19 :李:靖澜:315841211951
20 :涉:嫌诈:355689419549
21 :骗:一案:211941427311
22 :作:出二:955571796009
23 :审:判决:255316430295
24 :认:为该:100111260469
25 :案:一审:191062013444
26 :审:判程:810181455641
27 :序:违法:113989429322
28 :撤:销白:122462898754
29 :沙:黎族:129019204832
30 :自:治县:130177354708
31 :法:院作:356409173710
32 :出:的一:142157989866
33 :审:判决:966498972805
34 :并:发回:754956681892
35 :重:审据:122292775043
36 :媒:体此:130288589442
37 :前:报道:167944818461
38 :一:年前:172080133273
39 :岁:的成:111463746542
40 :都:女子:647386151035
41 :李:靖澜:187810033284
42 :被:曾经:155800602812
43 :先:后担:204946725517
44 :任:海南:198475481295
45 :湖:北两:115638320671
46 :地:副省:305175763940
47 :长:的孟:990708885468
48 :某:指称:504547666326
49 :其:诈骗:184865584447
50 :了:他的:449388324773
51 :钱:财李:167159632105
52 :靖:澜在:180880763687
53 :投:案后:213714639833
54 :被:取保:214336245698
55 :候:审一:131106491897
56 :年:后的:841392613317
57 :年:月日:570765049068
58 :她:被白:637375024988
59 :沙:县警:180128293428
60 :方:再次:509062487876
61 :以:涉嫌:805862930680
62 :诈:骗刑:198586716029
63 :拘:日被:145194043778
64 :当:地检:120526105741
65 :察:院批:188444725589
66 :捕:并在:196990170437
67 :日:起诉:591507055322
68 :至:法院:585094700076
69 :日:当地:126048583116
70 :法:院审:148190838373
71 :理:了这:179585206198
72 :一:案件:155761343494
73 :并:作出:103971760056
74 :判:决以:440293249476
75 :诈:骗罪:159458262590
76 :名:成立:100438421451
77 :判:处李:981875538956
78 :靖:澜有:203500673977
79 :期:徒刑:159608756642
80 :二:年零:232153432774
81 :六:个月:128436858284
82 :并:处罚:825950614970
83 :金:元有:157586901774
84 :法:律人:130563404667
85 :士:说白:122724627540
86 :沙:县公:774717205200
87 :检:法机:324936287248
88 :关:这样:482627880537
89 :的:办案:911535927842
90 :过:程堪:172139022250
91 :称:神速:110868313555
92 :公:检法:212255501853
93 :神:速办:161133326818
94 :案:拘捕:740888759669
95 :诉:判一:362298071384
96 :周:完成:140927864574
97 :根:据白:105463614133
98 :沙:县今:136229832873
99 :年:月日:150029483091
100 :检:察院:108231396040

[yaotong]

101 :制:作的:316233805129
102 :白:检刑:203592279052
103 :诉:号起:303539959030
104 :诉:书显:194058808039
105 :示:年月:148557258672
106 :日:年月:649741710105
107 :日:被告:914545808875
108 :人:李靖:150886644864
109 :澜:分别:207243395610
110 :在:海南:146476514827
111 :省:白沙:328535058050
112 :县:七坊:188084848509
113 :镇:海南:176169645547
114 :椰:花香:124792284945
115 :酒:业有:410259871335
116 :限:公司:381404272729
117 :和:山东:175207792260
118 :省:邹平:101897559430
119 :黛:溪山:333507904975
120 :庄:两地:108041642671
121 :与:椰花:156945666249
122 :香:酒公:869593889959
123 :司:法人:599424351084
124 :代:表孟:121939441183
125 :某:洽谈:146273675019
126 :有:关酒:162055920787
127 :业:合作:154779860549
128 :事:宜时:101904102650
129 :李:谎称:263757183628
130 :自:己是:788588830834
131 :某:机构:178957057113
132 :负:责人:752470258429
133 :谢:某某:110848683896
134 :助:理兼:142144903427
135 :主:任为:913826054715
136 :促:成合:224432433601
137 :作:李要:203539933295
138 :求:孟先:197546344106
139 :加:入该:117823756030
140 :机:构并:741804810419
141 :交:纳元:101138545952
142 :会:费年:803965396984
143 :月:日孟:181593974627
144 :在:海口:679382495067
145 :市:向李:977884174976
146 :提:供的:582935437595
147 :地:址汇:210750561337
148 :款:元同:638487372326
149 :年:月日:158483322864
150 :李:在山:121625366640
151 :东:省济:420205565185
152 :南:市邮:163227157102
153 :政:局邮:179977799377
154 :电:支局:852581518899
155 :将:该款:107393863927
156 :提:取但:190852630416
157 :未:帮孟:588889767466
158 :办:理入:213250071239
159 :会:事宜:122763886857
160 :案:发后:108290285017
161 :年:月日:113917453906
162 :被:告人:416083336813
163 :李:靖澜:180749899294
164 :到:四川:134378101716
165 :省:成都:140993296770
166 :市:公安:424196929165
167 :局:金牛:180560145924
168 :分:局营:264411505592
169 :门:口派:235686771379
170 :出:所投:159327398197
171 :案:白沙:673362733000
172 :县:检察:201766720773
173 :院:认为:613361408914
174 :被:告人:721062804164
175 :李:靖澜:300726374586
176 :无:视国:157174678936
177 :法:采用:178943970674
178 :虚:构事:151796152394
179 :实:隐瞒:128692043850
180 :真:相的:160204189629
181 :方:法骗:541844018265
182 :取:他人:309756017687
183 :财:物数:346790640841
184 :额:较大:130798960574
185 :其:行为:172858776410
186 :已:经触:182804470260
187 :犯:刑法:451482155057
188 :的:有关:247857159907
189 :规:定应:118608942387
190 :当:以诈:305568357118
191 :骗:追究:243931228124
192 :其:刑事:974481700764
193 :责:任白:161277277650
194 :沙:县法:147111207132
195 :院:月日:116515112103
196 :作:出的:158411347448
197 :白:刑初:936334730272
198 :字:第号:432964843480
199 :刑:事判:149270469613
200 :决:书显:622521916408
201 :示:李靖:936269298075
202 :澜:在年:498331607669
203 :月:日因:123895863855
204 :涉:嫌诈:114185725911
205 :骗:被白:134790324553
206 :沙:县公:343453598825
207 :安:局刑:108087445208
208 :事:拘留:206477838913
209 :月:日被:149172321318
210 :取:保候:198279184706
211 :审:年月:407249990301
212 :日:又因:720277617808
213 :本:案被:382385755675
214 :白:沙县:213367849192
215 :公:安局:980763191617
216 :刑:事拘:213976368618
217 :留:月日:209055867450
218 :被:执行:134037854295
219 :逮:捕白:202381783419
220 :沙:县检:938493992752
221 :察:院于:199718693026
222 :月:日向:103840895663
223 :白:沙县:191807940483
224 :法:院提:621802162248
225 :起:公诉:487338998676
226 :白:沙县:164889134890
227 :法:院于:880586498952
228 :同:日决:433030275677
229 :定:受理:134659460160
230 :并:于月:129529575964
231 :日:开庭:968265642108
232 :审:理此:999869392962
233 :案:当天:128175129498
234 :即:作出:136085882041
235 :判:决刑:183269038855
236 :事:案件:177694215723
237 :确:实可:133952792439
238 :以:当庭:154563934301
239 :作:出判:121298205658
240 :决:但从:804292557966
241 :整:个案:395079601773
242 :件:办理:158208507639
243 :情:况来:119021165224
244 :看:这个:194052264819
245 :案:子确:520709418833
246 :实:办得:405090727820
247 :有:点过:129653897137
248 :快:了海:149761211086
249 :南:一家:125341915395
250 :律:师事:753190012590
251 :务:所的:106013244583
252 :陈:律师:172348405278
253 :在:看过:158817027066
254 :李:靖澜:131224269850
255 :一:案的:133010568811
256 :相:关材:148177751933
257 :料:后对:172492356110
258 :记:者说:319701711538
259 :目:前刑:123503270677
260 :事:案件:186043363982
261 :超:期审:195439427382
262 :理:的情:131793529959
263 :况:比较:156016529060
264 :多:见但:926519900814
265 :快:捕快:143172188910
266 :诉:快判:209369941993
267 :的:案例:675391131088
268 :确:实不:122037589478
269 :是:很多:655696039976
270 :据:悉白:372898087199
271 :沙:县公:232742322542
272 :安:局最:186324722426
273 :初:接到:182503482157
274 :孟:某报:159582583763
275 :案:后上:332068396654
276 :网:追逃:700909687678
277 :李:靖澜:170123710601
278 :的:内容:164234812926
279 :是:称其:137427242067
280 :涉:嫌诈:175809768467
281 :骗:亿元:116868445963
282 :李:家人:961068100505
283 :得:知后:876856863758
284 :被:吓坏:640515770414
285 :了:带其:998168155856
286 :至:成都:107459296123
287 :市:金牛:327291846318
288 :分:局营:692599798737
289 :门:口派:158228137298
290 :出:所投:672970139821
291 :案:自首:177242733568
292 :后:经成:205627220360
293 :都:警方:187247316395
294 :与:白沙:155447268952
295 :警:方核:643329354859
296 :实:涉案:202394869858
297 :金:额亿:272786826729
298 :元:系白:140940951013
299 :沙:警方:168298152322
300 :笔:误正:112471402366