VRT 'tr', 'r', 'srcwin', 'a_gt' for vrt:// connection (OSGeo#8330)

autotest/gcore/vrt_read.py

@@ -1529,7 +1529,7 @@ def test_vrt_protocol():
 
     ## no op, simply ignored as with gdal_translate
     ds = gdal.Open("vrt://data/float32.tif?projwin_srs=OGC:CRS84")
-    assert ds
+    assert ds is not None
 
     ds = gdal.Open(
         "vrt://data/float32.tif?projwin_srs=OGC:CRS84&projwin=-117.6407,33.90027,-117.6292,33.89181"
@@ -1540,6 +1540,45 @@ def test_vrt_protocol():
     assert ds.GetRasterBand(1).XSize == 18
     assert ds.GetRasterBand(1).YSize == 16
 
+    with gdal.quiet_errors():
+        ds = gdal.Open("vrt://data/float32.tif?tr=120")
+        assert ds is None
+
+    ds = gdal.Open("vrt://data/float32.tif?tr=120,240")
+
+    assert ds.GetGeoTransform()[0] == 440720.0
+    assert ds.GetGeoTransform()[1] == 120.0
+    assert ds.GetGeoTransform()[5] == -240.0
+    assert ds.GetRasterBand(1).XSize == 10
+    assert ds.GetRasterBand(1).YSize == 5
+
+    ds = gdal.Open("vrt://data/float32.tif?r=bilinear&tr=120,240")
+    assert struct.unpack("f", ds.ReadRaster(0, 0, 1, 1))[0] == pytest.approx(
+        128.95408630371094
+    )  ## check values changed via bilinear
+
+    with gdal.quiet_errors():
+        ds = gdal.Open("vrt://data/float32.tif?srcwin=0,0,3")
+        assert ds is None
+
+    ds = gdal.Open("vrt://data/float32.tif?srcwin=2,3,8,5")
+    assert ds.GetRasterBand(1).XSize == 8
+    assert ds.GetRasterBand(1).YSize == 5
+    assert struct.unpack("f", ds.ReadRaster(0, 0, 1, 1))[0] == pytest.approx(
+        123.0
+    )  ## check value is correct
+
+    with gdal.quiet_errors():
+        ds = gdal.Open("vrt://data/float32.tif?a_gt=1,0,0,0,1")
+        assert ds is None
+
+    ds = gdal.Open("vrt://data/float32.tif?a_gt=0,1,0,0,0,1")
+    gdaltest.check_geotransform(
+        (0, 1, 0, 0, 0, 1),
+        ds.GetGeoTransform(),
+        1e-9,
+    )
+
 
 @pytest.mark.require_driver("BMP")
 def test_vrt_protocol_expand_option():

doc/source/drivers/raster/vrt.rst

@@ -1688,7 +1688,8 @@ For example:
 
 
 The supported options currently are ``bands``, ``a_srs``, ``a_ullr``, ``ovr``, ``expand``,
-``a_scale``, ``a_offset``, ``ot``, ``gcp``, ``if``, ``scale``, ``exponent``, ``outsize``, and ``projwin``.
+``a_scale``, ``a_offset``, ``ot``, ``gcp``, ``if``, ``scale``, ``exponent``, ``outsize``, ``projwin``,
+``tr``, ``r``, ``srcwin``, and ``a_gt``.
 
 Other options may be added in the future.
 
@@ -1748,6 +1749,16 @@ provided.
 
 The effect of the ``projwin_srs`` option (added in GDAL 3.8) is to specify the SRS in which to interpret the coordinates given with ``projwin`` in the same way as (:ref:`gdal_translate`). This option only applies if ``projwin`` is also supplied.
 
+The effect of the ``tr`` option (added in GDAL 3.8) is to set the target resolution, two positive values in georeferenced coordinates, applied in the same way as (:ref:`gdal_translate`). The value consists of two numeric values separated by commas in the order 'xres,yres'.
+
+The effect of the ``r`` option (added in GDAL 3.8) is to set the resampling algorithm used, with 'nearest' as the default. This is applied in the same way as (:ref:`gdal_translate`).
+
+The effect of the ``srcwin`` option (added in GDAL 3.8) is to select a subwindow from the source image based on pixel/line location as with (:ref:`gdal_translate`). The value consists of four integer values separated by commas, in
+the order 'xoff,yoff,xsize,ysize'.
+
+The effect of the ``a_gt`` option (added in GDAL 3.8) is to override/assign the geotransform of the output as with (:ref:`gdal_translate`). The value consists of six numeric values separated by commas, in
+the order 'gt(0),gt(1),gt(2),gt(3),gt(4),gt(5)'.
+
 
 The options may be chained together separated by '&'. (Beware the need for quoting to protect
 the ampersand).

frmts/vrt/vrtdataset.cpp

@@ -1228,7 +1228,78 @@ GDALDataset *VRTDataset::OpenVRTProtocol(const char *pszSpec)
                 argv.AddString("-projwin_srs");
                 argv.AddString(pszValue);
             }
+            else if (EQUAL(pszKey, "tr"))
+            {
+                CPLStringList aosTargetResolution(
+                    CSLTokenizeString2(pszValue, ",", 0));
+                if (aosTargetResolution.size() != 2)
+                {
+                    CPLError(CE_Failure, CPLE_IllegalArg,
+                             "Invalid tr option: %s, must be two "
+                             "values separated by comma xres,yres",
+                             pszValue);
+                    poSrcDS->ReleaseRef();
+                    CPLFree(pszKey);
+                    return nullptr;
+                }
+                argv.AddString("-tr");
+                argv.AddString(aosTargetResolution[0]);
+                argv.AddString(aosTargetResolution[1]);
+            }
+            else if (EQUAL(pszKey, "r"))
+            {
+                argv.AddString("-r");
+                argv.AddString(pszValue);
+            }
+
+            else if (EQUAL(pszKey, "srcwin"))
+            {
 
+                // Parse the limits
+                CPLStringList aosSrcWin(CSLTokenizeString2(pszValue, ",", 0));
+                // fail if not four values
+                if (aosSrcWin.size() != 4)
+                {
+                    CPLError(CE_Failure, CPLE_IllegalArg,
+                             "Invalid srcwin option: %s, must be four "
+                             "values separated by comma xoff,yoff,xsize,ysize",
+                             pszValue);
+                    poSrcDS->ReleaseRef();
+                    CPLFree(pszKey);
+                    return nullptr;
+                }
+
+                argv.AddString("-srcwin");
+                argv.AddString(aosSrcWin[0]);
+                argv.AddString(aosSrcWin[1]);
+                argv.AddString(aosSrcWin[2]);
+                argv.AddString(aosSrcWin[3]);
+            }
+
+            else if (EQUAL(pszKey, "a_gt"))
+            {
+
+                // Parse the limits
+                CPLStringList aosAGeoTransform(
+                    CSLTokenizeString2(pszValue, ",", 0));
+                // fail if not six values
+                if (aosAGeoTransform.size() != 6)
+                {
+                    CPLError(CE_Failure, CPLE_IllegalArg,
+                             "Invalid a_gt option: %s", pszValue);
+                    poSrcDS->ReleaseRef();
+                    CPLFree(pszKey);
+                    return nullptr;
+                }
+
+                argv.AddString("-a_gt");
+                argv.AddString(aosAGeoTransform[0]);
+                argv.AddString(aosAGeoTransform[1]);
+                argv.AddString(aosAGeoTransform[2]);
+                argv.AddString(aosAGeoTransform[3]);
+                argv.AddString(aosAGeoTransform[4]);
+                argv.AddString(aosAGeoTransform[5]);
+            }
             else
             {
                 CPLError(CE_Failure, CPLE_NotSupported, "Unknown option: %s",