Questions tagged [c++]
An object-oriented programming language
414
questions
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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/...
CommunityBot
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3
votes
1
answer
240
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QGIS - How to render QgsMapCanvas on QApplication's main window
I am working with C++, QT 5.11.3, Visual Studio 2015 and QGIS 3.7
I'm trying to develop QT c++ application that uses the qgis api. I want to display simple raster and vector map in my qt application. ...
CommunityBot
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1
vote
0
answers
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. ...
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0
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37
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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 ...
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-1
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1
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14
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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 ...
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0
votes
1
answer
33
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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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15
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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 ...
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6
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1
answer
198
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Match housenumbers on buildings (special case of point-in-polygon-test)
Task with example
I'm working with geodata (country-size) from openstreetmap. Buildings are often polygons without housenumbers and a single point with the housenumber is placed within the polygon of ...
CommunityBot
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2
votes
1
answer
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OGRFeature set Multiple fields
To start off with:
Using Gdal compiled with Xerces
Coding in C++ with the QT Creator version 5.4.1
So my problem is I'm trying to use Gdal to create my own Esri shapefile, I get a strange runtime ...
CommunityBot
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0
votes
2
answers
69
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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 ...
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0
answers
32
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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* ...
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1
vote
1
answer
37
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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::...
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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 ...
CommunityBot
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1
vote
0
answers
99
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C++ parser for OGC Filter Encoding 1.0
I'm developing a C++ application and I have to parse a OGC Filter in order to implement querying functionality on a metadata repository.
Does anyone know any C++ library to parse OGC Filters?
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1
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1
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129
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Show differenet SVG icons on one layer at runtime
I need to show several SVG icons (more than 388 icons) with different name on a single layer(if possible on memory layer). I am using QGis 2.8 and qt4.8.6 The icons represent different kind of ...
CommunityBot
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0
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26
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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 ...
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0
answers
20
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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(...
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1
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213
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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 {...
CommunityBot
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0
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88
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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 ...
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1
vote
1
answer
316
views
Undefined reference to mapnik::hit_grid from C++ compile?
I am trying to compile a c++ mapnik program with code in question being:
mapnik::grid my_grid(256, 256, "id");
and the command to compile being:
g++ grid_gen.cpp -std=c++11 -lmapnik -lcairo -...
CommunityBot
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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 ...
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1
vote
1
answer
161
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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 ...
CommunityBot
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1
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145
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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 ++?
2
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0
answers
733
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Setup of development environment of QGIS on windows with qt creator [closed]
Can anyone help me in setting up environment for working on QGIS on windows using qt-creator?
I am using qt creator version 1.3.1,qt version 4.6 and QGIS version 1.8.
- 64.9k
0
votes
1
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729
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Multispectral images (Band Sequential format) [closed]
How can I create a multispectral image file (in band sequential (BSQ) format), from several 1-band images, using GDAL libraries?
I work with C++ language.
- 64.9k
0
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2
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621
views
Requesting tiles without using XML file (GDAL C++) [closed]
I have been able to request a specific tile with my XML through GDAL lib.
However, is there is another way of requesting the tiles from a web server without using XML?
I want to do it directly through ...
- 64.9k
0
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0
answers
42
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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 ...
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1
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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 ...
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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);
...
- 64.9k
1
vote
1
answer
130
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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 ...
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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 (...
- 19.8k
14
votes
2
answers
14k
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Characteristics of different methods to convert ECEF to LLA
I'm trying to convert ECEF (Earth Centered, Earth Fixed) coordinates, which are defined in X,Y,Z, centered at (0,0,0) to LLA (Latitude, Longitude, Altitude). There are a couple of methods I found on ...
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3
votes
1
answer
385
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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 ...
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1
vote
1
answer
307
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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 ...
- 7,757
0
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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 ...
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0
votes
1
answer
367
views
Updated version of QGIS coding and compilation guide [closed]
Is there an updated version of QGIS coding and compilation guide?
The current version is clearly outdated. I have been trying to compile the first example, 1_hello_world_qgis_style, though to no avail ...
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0
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0
answers
20
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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 ...
13
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5
answers
16k
views
Converting latitude, longitude (EPSG:4326) into EPSG:3857?
I'm looking to study the math involved to see how a given latitude and longitude in decimal degrees can be converted to EPSG:3857. Can anybody point to a good reference or a possible Ppython/C/C++/...
- 19.8k
1
vote
0
answers
157
views
Stepping into C++ functions from external Python app while debugging [closed]
I just wanted to see how to step into the C++ class QgsVectorLayer()'s methods from the python call to QgsVectorLayer(self.uri.uri(),'foo','postgres'). I'm trying to debug and it trying to step into ...
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0
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2
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346
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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 ...
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1
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0
answers
78
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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 ...
- 64.9k
2
votes
1
answer
63
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QgsMapCanvas on-the-fly feature does not work
I am writing a simple program to display raster data using qgis api C++.
When I open raster data that has different coordinate systems, the on-the-fly feature does not work on my mapCanvas.
Can ...
CommunityBot
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4
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1
answer
1k
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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 ...
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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 ...
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2
votes
1
answer
145
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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 = &...
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2
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0
answers
32
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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&...
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1
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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 ...
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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);
...
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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\...
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1
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0
answers
137
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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 ...
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