- API: add new zint_symbol dpmm field for output resolution (BMP/

EMF/PCX/PNG/TIF only, i.e. excluding EPS, GIF & SVG)
- Add support for specifying scale by X-dimension and resolution
  with new option `--scalexdimdp` for CLI/Tcl & new API function
  `ZBarcode_Scale_From_XdimDp()` (+ `ZBarcode_XdimDp_From_Scale()`
  & `ZBarcode_Default_Xdim()`) and new GUI popup; manual: document
- BMP/EMF/PCX/PNG/TIF: use new `dpmm` resolution field (for EMF
  following Inkscape)
- backend_qt: add `dpmm()`, `vectorWidth()`, `vectorHeight()`,
  `noPng()`, `getVersion()`, `takesGS1AIData()`, & `XdimDp` stuff
  incl. new `QZintXdimDp` struct for passing around scale vars &
  use in `getAsCLI()`; add comments
- Raise `scale` limit to 200 (from 100) to allow for large dpmm
- output: create directories & subdirectories as necessary for
  output path using new function `out_fopen()` and use in BMP/EMF/
  EPS/GIF/PCX/PNG/SVG/TIF
- DPLEIT/DPIDENT: format HRT according to (incomplete)
  documentation, and set default height to 72X (from 50X)
- CODE128B renamed to CODE128AB as can use subsets A and/or B
- CODABAR: fix minimum height calc
- EMF: fix indexing of handles (zero-based not 1-based)
- GUI: fix symbology zap (previous technique of clearing and
  re-loading settings without doing a sync no longer works);
  fix UPCEAN guard descent enable
- MAILMARK: better error message if input < 14 characters
- GUI: add "Default" button for DAFT tracker ratio & enable/disable
  various default buttons; use new `takesGS1AIData()` to
  enable/disable GS1-specific checkboxes
- CLI: use new `validate_float()` to parse float options (7
  significant digits allowed only, no scientific notation)
- DATAMATRIX/GRIDMATRIX/PDF417/QR/ULTRA: micro-optimize structapp
  ID parse
- library/CLI: fiddle with static asserts (make CHAR_BIT sensitive,
  supposedly)
- win32/README: update building libpng (assembly removed)
- README.linux: document incompatibility of Qt6 >= 6.3
- manual: expand Barcode Studio waffle
- test suite: change range separator to hyphen and allow multiple
  excludes

backend/zint.h

@@ -111,6 +111,7 @@ extern "C" {
         int fontsize;       /* Unused */
         int input_mode;     /* Encoding of input data (see DATA_MODE etc below). Default DATA_MODE */
         int eci;            /* Extended Channel Interpretation. Default 0 (none) */
+        float dpmm;         /* Resolution of output in dots per mm (BMP/EMF/PCX/PNG/TIF only). Default 0 (none) */
         float dot_size;     /* Size of dots used in BARCODE_DOTTY_MODE. Default 0.8 */
         float guard_descent; /* Height in X-dimensions that EAN/UPC guard bars descend. Default 5 */
         struct zint_structapp structapp; /* Structured Append info. Default structapp.count 0 (none) */
@@ -184,7 +185,8 @@ extern "C" {
 #define BARCODE_PDF417TRUNC     56  /* Legacy */
 #define BARCODE_MAXICODE        57  /* MaxiCode */
 #define BARCODE_QRCODE          58  /* QR Code */
-#define BARCODE_CODE128B        60  /* Code 128 (Subset B) */
+#define BARCODE_CODE128AB       60  /* Code 128 (Suppress subset C) */
+#define BARCODE_CODE128B        60  /* Legacy */
 #define BARCODE_AUSPOST         63  /* Australia Post Standard Customer */
 #define BARCODE_AUSREPLY        66  /* Australia Post Reply Paid */
 #define BARCODE_AUSROUTE        67  /* Australia Post Routing */
@@ -322,7 +324,7 @@ extern "C" {
 #define ZINT_ERROR_USES_ECI         13  /* Error counterpart of warning if WARN_FAIL_ALL set (see below) */
 #define ZINT_ERROR_NONCOMPLIANT     14  /* Error counterpart of warning if WARN_FAIL_ALL set */
 
-/* Warning warn (`symbol->warn_level`) */
+/* Warning level (`symbol->warn_level`) */
 #define WARN_DEFAULT            0  /* Default behaviour */
 #define WARN_FAIL_ALL           2  /* Treat warning as error */
 
@@ -443,6 +445,19 @@ extern "C" {
     ZINT_EXTERN unsigned int ZBarcode_Cap(int symbol_id, unsigned int cap_flag);
 
 
+    /* Return default X-dimension in mm for symbology `symbol_id`. Returns 0 on error (invalid `symbol_id`) */
+    ZINT_EXTERN float ZBarcode_Default_Xdim(int symbol_id);
+
+    /* Return the scale to use for `symbol_id` for non-zero X-dimension `x_dim_mm` at `dpmm` dots per mm for
+       `filetype`. If `dpmm` zero defaults to 12. If `filetype` NULL/empty, defaults to "GIF". Returns 0 on error */
+    ZINT_EXTERN float ZBarcode_Scale_From_XdimDp(int symbol_id, float x_dim_mm, float dpmm, const char *filetype);
+
+    /* Reverse of `ZBarcode_Scale_From_XdimDp()` above to estimate the X-dimension or dpmm given non-zero `scale` and
+       non-zero `x_dim_mm_or_dpmm`. Return value bound to dpmm max not X-dimension max. Returns 0 on error */
+    ZINT_EXTERN float ZBarcode_XdimDp_From_Scale(int symbol_id, float scale, float x_dim_mm_or_dpmm,
+                        const char *filetype);
+
+
     /* Whether Zint built without PNG support */
     ZINT_EXTERN int ZBarcode_NoPng(void);