testing: better testing coverage of null image reader/writer (AcademySoftwareFoundation#4578)

This improves the mediocre testing line coverage in nullimageio.cpp from
50% to 95%.

* Test writing
* Test reading of tiled and MIP-mapped null images
* Test setting and reading of attributes
* Simplify some code
* Along the way, identified and fixed a nullimage bug -- it was
answering that it supported "rectangles" but had no write_rectangle
method. Testing works!

Signed-off-by: Larry Gritz <[email protected]>
Signed-off-by: Scott Wilson <[email protected]>

Author: lgritz

src/null.imageio/nullimageio.cpp

@@ -24,7 +24,10 @@ class NullOutput final : public ImageOutput {
     NullOutput() {}
     ~NullOutput() override {}
     const char* format_name(void) const override { return "null"; }
-    int supports(string_view /*feature*/) const override { return true; }
+    int supports(string_view feature) const override
+    {
+        return feature != "rectangles";
+    }
     bool open(const std::string& /*name*/, const ImageSpec& spec,
               OpenMode /*mode*/) override
     {
@@ -316,10 +319,10 @@ NullInput::open(const std::string& name, ImageSpec& newspec,
         }
     }
 
+    m_value.resize(m_topspec.pixel_bytes());  // default fills with 0's
     if (fvalue.size()) {
         // Convert float to the native type
         fvalue.resize(m_topspec.nchannels, 0.0f);
-        m_value.resize(m_topspec.pixel_bytes());
         convert_pixel_values(TypeFloat, fvalue.data(), m_topspec.format,
                              m_value.data(), m_topspec.nchannels);
     }
@@ -365,13 +368,10 @@ bool
 NullInput::read_native_scanline(int /*subimage*/, int /*miplevel*/, int /*y*/,
                                 int /*z*/, void* data)
 {
-    if (m_value.size()) {
-        size_t s = m_spec.pixel_bytes();
-        for (int x = 0; x < m_spec.width; ++x)
-            memcpy((char*)data + s * x, m_value.data(), s);
-    } else {
-        memset(data, 0, m_spec.scanline_bytes());
-    }
+    size_t s = m_spec.pixel_bytes();
+    OIIO_DASSERT(m_value.size() == s);
+    for (int x = 0; x < m_spec.width; ++x)
+        memcpy((char*)data + s * x, m_value.data(), s);
     return true;
 }
 
@@ -381,13 +381,10 @@ bool
 NullInput::read_native_tile(int /*subimage*/, int /*miplevel*/, int /*x*/,
                             int /*y*/, int /*z*/, void* data)
 {
-    if (m_value.size()) {
-        size_t s = m_spec.pixel_bytes();
-        for (size_t x = 0, e = m_spec.tile_pixels(); x < e; ++x)
-            memcpy((char*)data + s * x, m_value.data(), s);
-    } else {
-        memset(data, 0, m_spec.tile_bytes());
-    }
+    size_t s = m_spec.pixel_bytes();
+    OIIO_DASSERT(m_value.size() == s);
+    for (size_t x = 0, e = m_spec.tile_pixels(); x < e; ++x)
+        memcpy((char*)data + s * x, m_value.data(), s);
     return true;
 }
 

testsuite/null/ref/out.txt

@@ -1,6 +1,12 @@
-Reading foo.null?RES=640x480&CHANNELS=3&TYPE=uint8&PIXEL=0.25,0.5,1
-foo.null?RES=640x480&CHANNELS=3&TYPE=uint8&PIXEL=0.25,0.5,1 :  640 x  480, 3 channel, uint8 null
+Reading foo.null?RES=640x480&CHANNELS=3&TYPE=uint8&PIXEL=0.25,0.5,1&a=1&b=2.5&c=foo&string d=bar&e=float 3&f="baz"
+foo.null?RES=640x480&CHANNELS=3&TYPE=uint8&PIXEL=0.25,0.5,1&a=1&b=2.5&c=foo&string d=bar&e=float 3&f="baz" :  640 x  480, 3 channel, uint8 null
     channel list: R, G, B
+    a: 1
+    b: 2.5
+    c: "foo"
+    d: "bar"
+    e: 3
+    f: "baz"
     Stats Min: 64 128 255 (of 255)
     Stats Max: 64 128 255 (of 255)
     Stats Avg: 64.00 128.00 255.00 (of 255)
@@ -11,3 +17,22 @@ foo.null?RES=640x480&CHANNELS=3&TYPE=uint8&PIXEL=0.25,0.5,1 :  640 x  480, 3 cha
     Constant: Yes
     Constant Color: 64.00 128.00 255.00 (of 255)
     Monochrome: No
+Writing out.null
+Reading bar.null?RES=128x128&CHANNELS=3&TILE=64x64&TEX=1&TYPE=uint16&PIXEL=0.25,0.5,1
+bar.null?RES=128x128&CHANNELS=3&TILE=64x64&TEX=1&TYPE=uint16&PIXEL=0.25,0.5,1 :  128 x  128, 3 channel, uint16 null
+    MIP-map levels: 128x128 64x64 32x32 16x16 8x8 4x4 2x2 1x1
+    channel list: R, G, B
+    tile size: 64 x 64
+    textureformat: "Plain Texture"
+    wrapmodes: "black,black"
+      Stats Min: 16384 32768 65535 (of 65535)
+      Stats Max: 16384 32768 65535 (of 65535)
+      Stats Avg: 16384.00 32768.00 65535.00 (of 65535)
+      Stats StdDev: 0.00 0.00 0.00 (of 65535)
+      Stats NanCount: 0 0 0 
+      Stats InfCount: 0 0 0 
+      Stats FiniteCount: 16384 16384 16384 
+      Constant: Yes
+      Constant Color: 16384.00 32768.00 65535.00 (of 65535)
+      Monochrome: No
+Writing outtile.null

testsuite/null/run.py

@@ -5,4 +5,10 @@
 # https://github.com/AcademySoftwareFoundation/OpenImageIO
 
 
-command += oiiotool ('-v -info -stats "foo.null?RES=640x480&CHANNELS=3&TYPE=uint8&PIXEL=0.25,0.5,1"')
+# Read and write null scanline and a tiled mipmap image
+command += oiiotool ('-v -info -stats ' +
+                     '"foo.null?RES=640x480&CHANNELS=3&TYPE=uint8&PIXEL=0.25,0.5,1&a=1&b=2.5&c=foo&string d=bar&e=float 3&f=\\\"baz\\\"" ' +
+                     '-o out.null ' +
+                     '"bar.null?RES=128x128&CHANNELS=3&TILE=64x64&TEX=1&TYPE=uint16&PIXEL=0.25,0.5,1" ' +
+                     '-o:tile=64x64 outtile.null'
+                     )