pdf_add_line_pattern: Added ability to draw non-solid lines

pdfgen.c

@@ -3352,25 +3352,57 @@ int pdf_add_text_wrap(struct pdf_doc *pdf, struct pdf_object *page,
     return 0;
 }
 
-int pdf_add_line(struct pdf_doc *pdf, struct pdf_object *page, float x1,
-                 float y1, float x2, float y2, float width, uint32_t colour)
+int pdf_add_line_pattern(struct pdf_doc *pdf, struct pdf_object *page,
+                         float x1, float y1, float x2, float y2, float width,
+                         uint32_t colour, const float pattern[],
+                         int pattern_len, float phase)
 {
     int ret;
     struct dstr str = INIT_DSTR;
+    int nonzero = 0;
+
+    if (pattern_len < 0 || (pattern_len > 0 && !pattern))
+        return pdf_set_err(pdf, -EINVAL, "Invalid line pattern");
+    for (int i = 0; i < pattern_len; i++) {
+        if (pattern[i] < 0.0f)
+            return pdf_set_err(pdf, -EINVAL,
+                               "Line pattern lengths must be >= 0");
+        if (pattern[i] > 0.0f)
+            nonzero = 1;
+    }
+    if (pattern_len > 0 && !nonzero)
+        return pdf_set_err(pdf, -EINVAL,
+                           "Line pattern must have a non-zero length");
 
+    if (pattern_len > 0) {
+        dstr_append(&str, "[");
+        for (int i = 0; i < pattern_len; i++)
+            dstr_printf(&str, "%s%f", i ? " " : "", pattern[i]);
+        dstr_printf(&str, "] %f d\r\n", phase);
+    }
     dstr_printf(&str, "%f w\r\n", width);
     dstr_printf(&str, "%f %f m\r\n", x1, y1);
     dstr_printf(&str, "/DeviceRGB CS\r\n");
     dstr_printf(&str, "%f %f %f RG\r\n", PDF_RGB_R(colour), PDF_RGB_G(colour),
                 PDF_RGB_B(colour));
     dstr_printf(&str, "%f %f l S\r\n", x2, y2);
+    /* Restore the solid pattern */
+    if (pattern_len > 0)
+        dstr_append(&str, "[] 0 d\r\n");
 
     ret = pdf_add_stream(pdf, page, dstr_data(&str));
     dstr_free(&str);
 
     return ret;
 }
 
+int pdf_add_line(struct pdf_doc *pdf, struct pdf_object *page, float x1,
+                 float y1, float x2, float y2, float width, uint32_t colour)
+{
+    return pdf_add_line_pattern(pdf, page, x1, y1, x2, y2, width, colour,
+                                NULL, 0, 0.0f);
+}
+
 int pdf_add_cubic_bezier(struct pdf_doc *pdf, struct pdf_object *page,
                          float x1, float y1, float x2, float y2, float xq1,
                          float yq1, float xq2, float yq2, float width,

pdfgen.h

@@ -511,6 +511,28 @@ int pdf_add_text_wrap(struct pdf_doc *pdf, struct pdf_object *page,
 int pdf_add_line(struct pdf_doc *pdf, struct pdf_object *page, float x1,
                  float y1, float x2, float y2, float width, uint32_t colour);
 
+/**
+ * Add a line with a dash pattern (dashed/dotted etc...)
+ * @param pdf PDF document to add to
+ * @param page Page to add object to (NULL => most recently added page)
+ * @param x1 X offset of start of line
+ * @param y1 Y offset of start of line
+ * @param x2 X offset of end of line
+ * @param y2 Y offset of end of line
+ * @param width Width of the line
+ * @param colour Colour to draw the line
+ * @param pattern Array of alternating dash & gap lengths describing the
+ *        pattern, e.g. {6, 3} => dashed, {1, 2} => dotted. At least one
+ *        length must be non-zero
+ * @param pattern_len Number of entries in pattern (0 => solid line)
+ * @param phase Distance into the pattern at which to start the line
+ * @return 0 on success, < 0 on failure
+ */
+int pdf_add_line_pattern(struct pdf_doc *pdf, struct pdf_object *page,
+                         float x1, float y1, float x2, float y2, float width,
+                         uint32_t colour, const float pattern[],
+                         int pattern_len, float phase);
+
 /**
  * Add a cubic bezier curve to the document
  * @param pdf PDF document to add to

tests/main.c

@@ -114,6 +114,31 @@ int main(int argc, char *argv[])
     pdf_add_text(pdf, NULL, "Page One", 10, 20, 30, PDF_RGB(0xff, 0, 0));
     pdf_add_text(pdf, NULL, "PjGQji", 18, 20, 130, PDF_RGB(0, 0xff, 0xff));
     pdf_add_line(pdf, NULL, 10, 24, 100, 24, 4, PDF_RGB(0xff, 0, 0));
+    float dashed[] = {6, 3};
+    pdf_add_line_pattern(pdf, NULL, 10, 34, 100, 34, 2, PDF_RGB(0, 0x80, 0),
+                         dashed, 2, 0);
+    float dotted[] = {1, 2};
+    pdf_add_line_pattern(pdf, NULL, 10, 40, 100, 40, 2, PDF_RGB(0, 0, 0xff),
+                         dotted, 2, 0);
+    /* Invalid patterns should be rejected */
+    float all_zero[] = {0, 0};
+    if (pdf_add_line_pattern(pdf, NULL, 10, 46, 100, 46, 2, PDF_BLACK,
+                             all_zero, 2, 0) >= 0) {
+        fprintf(stderr, "All-zero line pattern not rejected\n");
+        return -1;
+    }
+    float negative[] = {3, -1};
+    if (pdf_add_line_pattern(pdf, NULL, 10, 46, 100, 46, 2, PDF_BLACK,
+                             negative, 2, 0) >= 0) {
+        fprintf(stderr, "Negative line pattern not rejected\n");
+        return -1;
+    }
+    if (pdf_add_line_pattern(pdf, NULL, 10, 46, 100, 46, 2, PDF_BLACK, NULL,
+                             2, 0) >= 0) {
+        fprintf(stderr, "NULL line pattern not rejected\n");
+        return -1;
+    }
+    pdf_clear_err(pdf);
     pdf_add_cubic_bezier(pdf, NULL, 10, 100, 150, 100, 20, 30, 60, 30, 4,
                          PDF_RGB(0, 0xff, 0));
     pdf_add_quadratic_bezier(pdf, NULL, 10, 140, 150, 140, 50, 160, 4,