Differential D19696 Diff 53699 thumbnail/blendercreator.cpp

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thumbnail/blendercreator.cpp

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1​/*
2​ * Copyright (c) 2019 Chinmoy Ranjan Pradhan <chinmoyrp65@gmail.com>
3​ *
4​ * This library is free software; you can redistribute it and/or
5​ * modify it under the terms of the GNU Lesser General Public
6​ * License as published by the Free Software Foundation; either
7​ * version 2.1 of the License, or (at your option) version 3, or any
8​ * later version accepted by the membership of KDE e.V. (or its
9​ * successor approved by the membership of KDE e.V.), which shall
10​ * act as a proxy defined in Section 6 of version 3 of the license.
11​ *
12​ * This library is distributed in the hope that it will be useful,
13​ * but WITHOUT ANY WARRANTY; without even the implied warranty of
14​ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15​ * Lesser General Public License for more details.
16​ *
17​ * You should have received a copy of the GNU Lesser General Public
18​ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
19​ */
20​
21​#include "blendercreator.h"
22​
23​#include <assert.h>
24​#include <zlib.h>
25​
26​#include <QFile>
27​#include <QImage>
28​#include <QPointer>
29​#include <QDebug>
30​
31​#include <KCompressionDevice>
32​
33​extern "C"
34​{
35​ Q_DECL_EXPORT ThumbCreator *new_creator()
36​ {
37​ return new BlenderCreator;
38​ }
39​}
40​
41​BlenderCreator::BlenderCreator() = default;
42​
43​BlenderCreator::~BlenderCreator() = default;
44​
45​// For more info. see https://developer.blender.org/diffusion/B/browse/master/release/bin/blender-thumbnailer.py
46​
47​bool BlenderCreator::create(const QString &path, int width , int height, QImage &img)
48​{
49​ QFile file (path);
50​ if(!file.open(QIODevice::ReadOnly)) {
51​ return false;
52​ }
53​
54​ QDataStream blendStream;
55​ blendStream.setDevice(&file);
56​ QPointer<KCompressionDevice> gzFile;
57​ if(file.peek(2).startsWith("\x1F\x8B")) { // gzip magic (each gzip member starts with ID1(0x1f) and ID2(0x8b))
brunsUnsubmitted
Not Done

I think this is already done by the calling code - the thumbnailer gets only called when the mimetype matches.

bruns: I think this is already done by the calling code - the thumbnailer gets only called when the…
chinmoyrAuthorUnsubmitted
Not Done

This part is required because blender can save files with gzip compression. Examples here : https://download.blender.org/demo/test/Demo_274.zip. For some of them properties dialog shows "Contents: application/gzip".

chinmoyr: This part is required because blender can save files with gzip compression. Examples here…
58​ file.close();
59​ gzFile = new KCompressionDevice(path, KCompressionDevice::GZip);
60​ if (gzFile->open(QIODevice::ReadOnly)) {
61​ blendStream.setDevice(gzFile);
62​ }
brunsUnsubmitted
Done

} else { ...?

bruns: `} else {` ...?
63​ }
64​
65​ // First to check is file header.
66​ // BLEND file header format
67​ // Reference Content Size
68​ // id "BLENDER" 7
69​ // pointer-size _ (underscore)(32 bit)/ - (minus)(64 bit) 1
70​ // endianness v (little) / V (big) 1
71​ // version "248" = 2.48 etc. 3
72​
73​ // Example header: "BLENDER-257"
brunsUnsubmitted
Done

This is missing the 'v' / 'V'

bruns: This is missing the 'v' / 'V'
74​
75​ char head[12];
76​ blendStream.readRawData(head, 12);
77​ const QByteArray headBytes = QByteArray::fromRawData(head, 12);
78​ if(!headBytes.startsWith("BLENDER") || headBytes.right(3).toInt() < 250 /*blender pre 2.5 had no thumbs*/) {
79​ blendStream.device()->close();
80​ return false;
81​ }
82​
83​ // Next is file block. This we have to skip.
84​ // File block header format
85​ // Reference Content Size
86​ // 1. id "REND","TEST", etc. 4
87​ // 2. size Total length of the data after the file-block-header 4
88​ // 3. old mem. addr Mem. address. pointer-size i.e, 4(32bit)/8(64bit)
89​ // 4. SDNA index Index of SDNA struct 4
90​ // 5. count No. of struct in file-block 4
91​
92​ const bool isLittleEndian = head[8] == 'v';
93​ if(isLittleEndian) {
94​ blendStream.setByteOrder(QDataStream::LittleEndian);
95​ } else {
96​ blendStream.setByteOrder(QDataStream::BigEndian);
97​ }
98​ const qint32 REND = isLittleEndian ? 1145980242 /*python int.from_bytes(b'REND', byteorder='little')*/ : 1380273732;
brunsUnsubmitted
Done

When you write these as hex, it becomes more obvious one is "REND" while the other is "DNER". Although ...

bruns: When you write these as hex, it becomes more obvious one is "REND" while the other is "DNER".
99​ const qint32 TEST = isLittleEndian ? 1414743380 : 1413829460;
100​ const bool is64Bit = head[7] == '-';
101​ const int fileBlockHeadSize = is64Bit ? 24 : 20; // sum(1 through 6)
brunsUnsubmitted
Done

Does this mean 'size of header fields 1 to 5'?

bruns: Does this mean 'size of header fields 1 to 5'?
chinmoyrAuthorUnsubmitted
Not Done

yes

chinmoyr: yes
102​ const int remainingHeader = fileBlockHeadSize - 8; // sum(3 through 5)
103​ qint32 code = 0, length = 0;
104​ while (true) {
105​ blendStream >> code >> length;
brunsUnsubmitted
Not Done

... you can use readRawData(data, 4) here and just compare with 'REND'.

Or even always read the whole header, saving you the skipRawData(remainingHeader), and gets rid of remainingHeader.

Actually, using operator>> on raw data, i.e. anything not written using QDataStream is dangerous. There is no guarantee an int is serialized as just 4 bytes.

bruns: ... you can use `readRawData(data, 4)` here and just compare with 'REND'. Or even always read…
106​ if (code == REND) {
107​ // Already passed through 1 & 2. Next, to skip section 3-5 + actual file-block data.
108​ blendStream.skipRawData(remainingHeader + length);
109​ } else {
110​ break;
111​ }
112​ }
113​
114​ if(code != TEST) {
115​ blendStream.device()->close();
116​ return false;
117​ }
118​ // For "TEST" there's nothing after header.
119​ blendStream.skipRawData(remainingHeader);
120​
121​ // Now comes actual thumbnail image data.
122​ quint32 x = 0, y = 0;
123​ blendStream >> x;
124​ blendStream >> y;
125​
126​ length = length - 8;
127​ if (length != x * y * 4) {
128​ blendStream.device()->close();
129​ return false;
130​ }
131​
132​ char *imgBuffer = new char[length];
133​ blendStream.readRawData(imgBuffer, length);
134​ abgr_to_argb(imgBuffer, length);
brunsUnsubmitted
Not Done

https://doc.qt.io/qt-5/qimage.html#rgbSwapped-1

bruns: https://doc.qt.io/qt-5/qimage.html#rgbSwapped-1
chinmoyrAuthorUnsubmitted
Not Done

I am trying to swap bgr to rgb here.

chinmoyr: I am trying to swap bgr to rgb here.
brunsUnsubmitted
Not Done

So does the code I linked to. No need to cook your own.

bruns: So does the code I linked to. No need to cook your own.
chinmoyrAuthorUnsubmitted
Not Done

Ah, sorry. I misunderstood what was written in doc. It really does swap them.

chinmoyr: Ah, sorry. I misunderstood what was written in doc. It really does swap them.
135​ QImage thumbnail((unsigned char*)imgBuffer, x, y, QImage::Format_ARGB32);
136​ if(width != 128) {
137​ thumbnail = thumbnail.scaledToWidth(width, Qt::SmoothTransformation);
138​ }
139​ if(height != 128) {
140​ thumbnail = thumbnail.scaledToHeight(height, Qt::SmoothTransformation);
141​ }
142​ thumbnail = thumbnail.mirrored();
143​ img = thumbnail.convertToFormat(QImage::Format_ARGB32_Premultiplied);
144​
145​ delete imgBuffer;
146​ blendStream.device()->close();
147​ return true;
148​}
149​
150​void BlenderCreator::abgr_to_argb(char *buf, int size) const
151​{
152​ char tmp;
153​ for (int i=0; i < size; i+=4) {
154​ tmp = buf[i];
155​ buf[i] = buf[i + 2];
156​ buf[i + 2] = tmp;
157​ }
158​}