[lmi-commits] [lmi] master a629602 083/156: Use custom <scaled_image> HTML tag for the embedded images

[Greg Chicares]

branch: master
commit a6296020d7920062e1792a166d90a5868a9853cd
Author: Vadim Zeitlin <address@hidden>
Commit: Vadim Zeitlin <address@hidden>

    Use custom <scaled_image> HTML tag for the embedded images
    
    Unfortunately the standard <a> tag can't be used to achieve the scaling
    we need as it's limited to integer height and width values, while we
    need fractional ones to obtain both the exact image size and aspect
    ratio and even the slight difference in the latter results in
    catastrophic visual consequences as the image becomes blurred due to
    resizing.
    
    Add custom <scaled_image> tag with its "inv_factor" attribute that can
    be used to specify exactly the scaling factor needed in HTML, at least
    for the values currently being used. And apply these values,
    corresponding to the scaling factors of 5/3 and (5/3)^2, to the logos on
    the cover page and in the headers of the other pages, respectively.
---
 cover.mustache                  |   2 +-
 header.mustache                 |   2 +-
 ledger_pdf_generator_wx.cpp     | 113 ++++++++++++++++++++++++++++++++++++++++
 narrative_summary_cont.mustache |   2 +-
 4 files changed, 116 insertions(+), 3 deletions(-)

diff --git a/cover.mustache b/cover.mustache
index 2d50a46..1245be4 100644
--- a/cover.mustache
+++ b/cover.mustache
@@ -112,7 +112,7 @@ it roughly where we want it to appear.
 <br></br>
 <br></br>
 
-<p align="center"><img src="company_logo.png"></img></p>
+<p align="center"><scaled_image inv_factor="0.6" 
src="company_logo.png"></scaled_image></p>
 
 <br></br>
 <br></br>
diff --git a/header.mustache b/header.mustache
index 7b3c21a..514388a 100644
--- a/header.mustache
+++ b/header.mustache
@@ -1,4 +1,4 @@
-<img src="company_logo.png"></img>
+<scaled_image inv_factor="0.36" src="company_logo.png"></scaled_image>
 
 <font size=-1>
 <p align="center">
diff --git a/ledger_pdf_generator_wx.cpp b/ledger_pdf_generator_wx.cpp
index 9610646..722ec02 100644
--- a/ledger_pdf_generator_wx.cpp
+++ b/ledger_pdf_generator_wx.cpp
@@ -44,6 +44,9 @@
 
 #include <wx/pdfdc.h>
 
+#include <wx/image.h>
+#include <wx/log.h>
+
 #include <wx/html/m_templ.h>
 
 #include <cstdint>                      // SIZE_MAX
@@ -466,6 +469,115 @@ class html_cell_for_pdf_output : public wxHtmlCell
 html_cell_for_pdf_output::pdf_context
 html_cell_for_pdf_output::pdf_context_for_html_output;
 
+// Define scaffolding for a custom HTML "scaled_image" tag which must be used
+// instead of the standard "a" in order to allow specifying the scaling factor
+// that we want to use for the image in the PDF. Unfortunately this can't be
+// achieved by simply using "width" and/or "height" attributes of the "a" tag
+// because their values can only be integers which is not precise enough to
+// avoid (slightly but noticeably) distorting the image due to the aspect ratio
+// being not quite right.
+
+class scaled_image_cell : public html_cell_for_pdf_output
+{
+  public:
+    scaled_image_cell
+        (wxImage const& image
+        ,wxString const& src
+        ,double scale_factor
+        )
+        :image_(image)
+        ,src_(src)
+        ,scale_factor_(scale_factor)
+    {
+        m_Width  = wxRound(image.GetWidth () / scale_factor);
+        m_Height = wxRound(image.GetHeight() / scale_factor);
+    }
+
+    // Override the base class method to actually render the image.
+    void Draw
+        (wxDC& dc
+        ,int x
+        ,int y
+        ,int view_y1
+        ,int view_y2,
+        wxHtmlRenderingInfo& info
+        ) override
+    {
+        draw_check_precondition(dc, view_y1, view_y2, info);
+
+        auto& writer = pdf_context_for_html_output.writer();
+
+        x += m_PosX;
+
+        int pos_y = y + m_PosY;
+        writer.output_image(image_, src_.utf8_str(), scale_factor_, x, &pos_y);
+    }
+
+  private:
+    wxImage const image_;
+    wxString const src_;
+    double const scale_factor_;
+};
+
+TAG_HANDLER_BEGIN(scaled_image, "SCALED_IMAGE")
+    TAG_HANDLER_PROC(tag)
+    {
+        wxString src;
+        if (!tag.GetParamAsString("SRC", &src))
+            {
+            throw std::runtime_error
+                ("missing mandatory \"src\" attribute of \"scaled_image\" tag"
+                );
+            }
+
+        // The scale factor is optional.
+        double scale_factor = 1.;
+
+        // But if it is given, we currently specify its inverse in HTML just
+        // because it so happens that for the scale factors we use the inverse
+        // can be expressed exactly in decimal notation, while the factor
+        // itself can't. In principle, the converse could also happen and we
+        // might add support for "factor" attribute too in this case. Or we
+        // could use separate "numerator" and "denominator" attributes. But for
+        // now implement just the bare minimum of what we need.
+        wxString inv_factor_str;
+        if (tag.GetParamAsString("INV_FACTOR", &inv_factor_str))
+            {
+            double inv_factor = 0.;
+            if (!inv_factor_str.ToCDouble(&inv_factor) || inv_factor == 0.)
+                {
+                throw std::runtime_error
+                    ( "invalid value for \"inv_factor\" attribute of "
+                      "\"scaled_image\" tag: \""
+                    + inv_factor_str.ToStdString()
+                    + "\""
+                    );
+                }
+
+            scale_factor = 1./inv_factor;
+            }
+
+        wxImage image;
+        // Disable error logging, we'll simply ignore the tag if the image is
+        // not present.
+            {
+            wxLogNull noLog;
+            image.LoadFile(src);
+            }
+
+        if (image.IsOk())
+            {
+            m_WParser->GetContainer()->InsertCell
+                (new scaled_image_cell(image, src, scale_factor)
+                );
+            }
+
+        // This tag isn't supposed to have any inner contents, so return true
+        // to not even try parsing it.
+        return true;
+    }
+TAG_HANDLER_END(scaled_image)
+
 class page
 {
   public:
@@ -1189,6 +1301,7 @@ TAG_HANDLER_END(numeric_summary_table)
 wxGCC_WARNING_SUPPRESS(pedantic)
 
 TAGS_MODULE_BEGIN(lmi_illustration)
+    TAGS_MODULE_ADD(scaled_image)
     TAGS_MODULE_ADD(numeric_summary_table)
 TAGS_MODULE_END(lmi_illustration)
 
diff --git a/narrative_summary_cont.mustache b/narrative_summary_cont.mustache
index 3737024..045003f 100644
--- a/narrative_summary_cont.mustache
+++ b/narrative_summary_cont.mustache
@@ -1,5 +1,5 @@
 <!-- No header for this page, just the logo -->
-<img src="company_logo.png"></img>
+<scaled_image inv_factor="0.36" src="company_logo.png"></scaled_image>
 
 <p align="center">NARRATIVE SUMMARY (Continued)</p>