Questions tagged [c++]
An object-oriented programming language
414
questions
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49
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Add one OpenGL object like QOpenGLWidget in QgsMapCanvas in a correct lat and lon
I want to add a large number of points to a QgsMapCanvas in a way that updates them every 100 milliseconds. In my initial attempt, I used QgsMapCanvasItem and QPainter to draw these points on the map. ...
- 121
0
votes
0
answers
37
views
How to make use of tile caching in QGIS using the C++ API?
I can load TMS Maps using C++ API of QGIS but as zoomIn/zoomOut Map it takes time to show map again.I want it to be smoother. I understand that QGIS has classes like QgsNetworkDiskCache or ...
- 121
-1
votes
1
answer
14
views
Microsoft C++exception occurred in vs2019 when using pdal debug mode: std:: bad_ Alloc's situation
On the debug x64 platform, running the code to (las_opts. add (las_opt)) will throw an exception, std:: bad_ Alloc's situation.
When I switch to release x-64 mode, it can run normally.
I don't know if ...
- 1
0
votes
1
answer
33
views
qgis._core.QgsLayoutTable represents a C++ abstract class and cannot be instantiated
When i try to access the QgsLayoutTable class it says that it is abstract, but in the documentation it is referred as a builder exactly as a QgsLayoutItemTextTable or QgsLayoutItemAttributeTable. ...
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1
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0
answers
15
views
Customizing popup using C++ Qt SDK
I have a KML layer on my map. I want to have a customized popup that will appear on click of placemark on my KML layer. I want to have customized fields in my popup.
I am using C++ qt SDK and tried to ...
- 11
0
votes
0
answers
32
views
GDAL keeps giving me a error C++
I have this code
float scalingFactor = 1.0f / 2.122f;
GDALAllRegister();
const char* filename = "C:/Users/awips/Desktop/BOLTgui/BOLT/test.nc";
GDALDataset* ...
0
votes
2
answers
69
views
Reading MrSID (.sid) files with a GDAL built by vcpkg
I have built GDAL 3.7.0 with vcpkg, creating ..\Documents\vcpkg\installed\x86-windows\lib\gdal.lib (I make a .lib to statically link into my C++ application). It is my understanding that when vcpkg ...
- 503
1
vote
1
answer
37
views
Is it possible to write your processing provider in C++ as a plugin?
Added a processing provider to his plugin, the plugin stopped downloading. Maybe c++ cannot be created at all.
plugin.cpp
void MyPlugins::initGui()
{
initProcessing();
}
void MyPlugins::...
- 11
0
votes
0
answers
26
views
QGIS C++ Custom Point Feature label Placement
I am using QGIS and C++for secondary development, and I want to customize the method of placing point feature labels. Based on mathematical rules, I will re select candidate label positions for point ...
- 1
0
votes
0
answers
20
views
GDALTranslate output has not Coordinate Reference System when chunking raster C++
I am trying to take a chunk from a raster file using the GDAL library in C++. Here is the code I am using:
const char * inputFile = "water_mask.img";
auto *dataset = (GDALDataset*) GDALOpen(...
- 111
0
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0
answers
89
views
How to convert point in any CRS to cartesian XYZ given the proj4 string?
I have GeoTIFFs of other celestial bodies, such as the moon, and am writing a program in C/C++. I cannot use GDAL but I can use libgeotiff, libtiff, and proj. Some GeoTIFFs are in a polar ...
- 111
1
vote
0
answers
64
views
Show/hide sublayers, QGIS API C++
I'm loading .osm map using QGIS API C++ 3.22.4.
The map has several sublayers (points, lines, multilinestrings...)
I'm trying to switch on/off sublayers with setSubLayerVisibility(), but always ...
- 11
0
votes
0
answers
43
views
Change cursor of QgsMaptoolPan in QGIS programmatically
I try to change cursor shape of QgsMaptoolPan using C++ without success.
I've connected the QgsMapTool::activated signal to a slot onPanActivate in a QgsMapCanvas Class.
in the slot, simply
QCursor ...
- 31
1
vote
0
answers
99
views
Cannot propagate events from QgsMapCanvas to QgsMapCanvasItem
I've extended the QgsMapCanvas to catch mouse events and all works well.
Then I try to catch events from a QgsMapCanvasItem. Reading the classes QgsMapCanvas extends QgraphicsView, and ...
- 31
0
votes
0
answers
38
views
Update position of QgsVertexMarker programmatically
I'm wondering how to update the position of a QgsVertexMarker.
Using C++ I have this code to create a Marker :
QgsVertexMarker *marker = new QgsVertexMarker(myMapCanvas);
marker->setCenter(centre);
...
- 31
0
votes
0
answers
27
views
Use GDAL (C++) to construct GeoTIFF from old one, but with modified data
I am trying to accomplish the following using GDAL with C++. Namely, starting from a GeoTIFF viewshed raster I want to construct a new GeoTIFF raster file with the same underlying properties (...
3
votes
1
answer
385
views
Copied the red band of the RGB TIFF file with GDAL in C++
I'm a rookie in GDAL and C++. I tried to copy the red band of the RGB tif file with Create() and GetRasterBand(1)->RasterIO(). I got the right size of my new tif file, but all the value of the new ...
- 31
1
vote
1
answer
307
views
GDAL warp in C++
What is the equivalent to the following GDAL terminal command in C++? I looked into GDAL C++ API, but could not figure it out.
gdalwarp -te xmin ymin xmax ymax -ts 1 1 -r max input.vrt output.vrt
for ...
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0
votes
1
answer
184
views
Detecting empty TIFFs [closed]
How to detect if a TIFF or VRT is empty. I don't want to loop all over values.
By empty, I mean full of NODATA values.
A C++ method is preferred.
Using the flag -stats with gdalinfo I can get ...
- 21
0
votes
0
answers
20
views
How to convert a TIF file into a bmp file in C++ 98? [duplicate]
I am new in C++? How i can convert TIF file into a bmp file in C++ 98 without any library?
Here is the link i found with library ?link
Here is my code but it is giving me error.I have taken it from ...
1
vote
1
answer
195
views
QGIS Building From Source Code with QtCreator in Windows 10 - Flex Dependency
My end objective is to develop QGIS plugins using C++ for a Windows 10 target machine, and to use QtCreator as the software development and build environment.
Following https://docs.qgis.org/3.22/en/...
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0
votes
1
answer
145
views
Using QGIS processing algorithms in C++
There are no instructions for using QGIS processing algorithms in the C ++ programming language but it exists in the Python language.
Is it possible to use QGIS processing algorithms in C ++?
0
votes
2
answers
348
views
Transforming using ntv2 nadgrids is behaving different between GDAL 2.3.1 and GDAL 3.4.2
I am working on upgrading to a newer version of GDAL and have an issue transforming coordinates using nadgrids (the beta2007.gsb ntv2 file which can be downloaded here) using GDAL 3.4.2.
The issue is ...
- 441
1
vote
1
answer
130
views
Custom map pan tool freezes map canvas extent, cuts off map tiles (QGIS 3.18)
I've written my own QGIS map tool class to access the protected member functions (canvasPressEvent, canvasReleaseEvent, etc) as well as to be able to limit the distance panned. Specifically I've ...
- 175
2
votes
1
answer
145
views
How to run QGIS 3 processing tool (DISSOLVE) in c++
For my QGIS C++ Plugin I have to run the QgsDissolveAlgorithm- processing tool.
I have found an example, how to do that in python:
import processing
infn = "path/to/dissolve"
outfn2 = &...
- 1,181
2
votes
0
answers
32
views
Change default point symbol with an icon in QGIS using API [duplicate]
I want to change default point symbol in the vector layer with an icon, which is an image in .png type using QGIS API.
I found a question "Creating custom marker from vector image using PyQGIS&...
- 93
1
vote
1
answer
255
views
Change point with icon in QGIS using API [closed]
I want to change points in the vector layer with an icon, which is an image in .png type using QGIS C++.
I found Creating custom marker from vector image using PyQGIS but how can I do that ...
- 93
2
votes
1
answer
130
views
Separate left and right mouse clicks when clicking on canvas
I want to call some functions when I click left and right on the canvas. I wrote the following code for this:
mpMapCanvas = new QgsMapCanvas();
mpClickPoint = new QgsMapToolEmitPoint(mpMapCanvas);
...
- 93
1
vote
1
answer
270
views
Opening GRASS GIS 7.8.4 Results in Error
When trying to create a new location in GRASS GIS 7.8.4 on a machine running Windows 11 I get the following error:
Traceback (most recent call last):
File "C:\PROGRA~1\QGIS32~1.1\apps\grass\...
- 761
1
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0
answers
137
views
PDAL LAS writer, how to set the writer as a output stream?
I have a C++ script for my lidar data processing and map building. However, there is no example to set the output stream. So how should I set up the output in the calculation function? The code is ...
- 133
1
vote
0
answers
207
views
put marker on a vector layer / map Qt-Qgis
I am designing a GUI using Qt and QGIS and showing maps (shapefiles - Vector layers) on the GUI. I want to put a marker on the vector layers when I click somewhere on the map. I could get coordinates ...
- 93
1
vote
0
answers
78
views
Setting mesh layer visibility in QGIS application?
I am utilizing the QgsMeshLayer class to load a NetCDF file that contains multiple variables (temperature, velocity, etc). I want to be able to set the visible dataset by variable name. I know how ...
- 175
1
vote
0
answers
228
views
Using QGIS Library in Qt Creator
I wanted to create a GUI in Qt Creator using QGIS libraries. I followed build steps and could build QGIS in Qt Creator. I can open the application from Qt Creator.
I have created a GUI using QT ...
- 93
1
vote
0
answers
572
views
Undefined reference to `proj_context_create' while run PROJ example
I have installed Proj 6.3.1 and I tried to run a Proj example from https://proj.org/development/quickstart.html. I implemented it with CLion on Ubuntu 20.04. And I got many undefined reference errors ...
- 11
1
vote
0
answers
512
views
Setup QGIS to use in C++ Qt Application
I have been working on a Qt5 Widgets based application. I'm required to display maps (vector charts) in my application on a widget and for that purpose I've decided to use the QGIS library in my ...
- 133
4
votes
1
answer
1k
views
How to speed up rasterio.transform.xy
REPRODUCIBLE SETUP
In a Google Colab notebook, I install rasterio:
!pip3 install rasterio
Import modules:
import rasterio
import numpy as np
import time
from rasterio.crs import CRS
from rasterio ...
- 1,308
3
votes
1
answer
114
views
.gdb table creation speed
I'm trying to convert a shapefile containing N single point shapes to a .gdb using the FileGDBAPI for C++ from Esri.
The structure of the shapefile is:
x | y | date1 | date2 | ...
- 143
1
vote
0
answers
52
views
What toolchain for a Win10 C++/Qt QGis custom application based on QGis v3.20?
We have a C++/Qt application based on the KDE Marble library. I would like to replace the Marble library with the QGis library. However it is not too easy to figure out the correct environment for ...
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1
vote
1
answer
313
views
GDALWarpOperation in C++ with cutline
I am currently trying to crop a raster by mask layer using the C++ GDAL API. I am using the GDALWarpOptions struct.
GDALWarpOptions *psWO = GDALCreateWarpOptions();
I then enter all the necessary ...
- 31
1
vote
1
answer
415
views
Reprojecting vector geometry in place using C++ & GDAL
I'm trying to implement a reprojection method in my C++ code using GDAL. I open a shape file, pass the pointer to the layer object to my method, and iterate through the features while retrojecting ...
- 455
0
votes
1
answer
213
views
List supported WKT spatial references in GDAL, c++
I would like to ask if I can retrieve a list of supported projections from GDAL API.
I am trying to use GDAL to coordinate transformation for my internal data in the following way.
struct MyConverter {...
1
vote
0
answers
77
views
Symbol change of line and polygon vector layer
I am trying to change the symbols of the polygon/ line vector layer using QGIS C++ APIs.
I am able to change the symbol of the point vector layer using below code. I am able to change the color for ...
- 95
2
votes
0
answers
273
views
Problem on running a sample code of QGIS3 C++ API
I have written a code using QGIS 3 C++ API. But there are runtime errors. My environment is:
Windows 10 64bit
Qt 5.15.1(MSVC 2019)
Qt Creator 4.13.1
QGIS 3.x.x
using osgeo4w-setup-x86_64.exe, and ...
- 51
1
vote
1
answer
161
views
QGIS 3 C++ API, QgsApplication crash
I'm trying to create a simple application using QGIS 3 SDK. I have used osgeo4w-setup-x86_64.exe for installing QGIS, and I have also installed qgis-dev and qgis-ltr-dev and Qt5. I have set up my .pro ...
- 51
1
vote
0
answers
121
views
Setting layer visibilty in custom QGIS 3.x application (C++ versus Python)
In my QGIS application, I would like to be able to have a QDialog window pop upon clicking a toolbar icon which lists the layers set to the map canvas, and have QCheckBoxes that allow the user to show/...
- 175
1
vote
0
answers
102
views
Hide layers with custom widget in QGIS 3.10 (C++)
I have written a custom application that loads multiple QgsMapLayers onto a basemap (OpenStreetMap raster tiles). I am attempting to include a menu option that allows the user to hide or show one or ...
- 175
3
votes
0
answers
520
views
Loading online OSM raster tiles using URL in custom QGIS application (C++)
I am trying to write a C++ version of a custom QGIS (v 3.10) application I initially wrote in Python that overlays data onto OpenStreetMap. I am able to do this successfully by loading online tiles ...
- 175
1
vote
0
answers
354
views
Cannot Compile and add GDAL library for Visual C++ project in Visual Studio IDE
I wanted o create a project using the GDAL library and its API for C code.
I can create an executable for this code by entering the following on the command line in a Linux Machine:
gcc -o myprogram ...
- 405
3
votes
1
answer
180
views
GDAL - Register Pixel Function for Command-Line Utilities
I'm new to GDAL and am just learning the inner-workings of C++ compilation at the moment so please bear with me.
I am trying to define a pixel function to produce a VRT from input TIFs, with a band ...
- 41
3
votes
1
answer
191
views
Modifying QGIS Project with C++
I have a QGIS project file, it has a point layer in GPKG format and online map layers. Coordinate System of online map layers is WGS 84 / Pseudo-Mercator. Point layer's default coordinate system is ...
- 281