update slide content

resources/slides.lua

 gShowBounds = false
 
 gPath = "/skia/trunk/resources/"
 
 function load_file(file)
     local prev_path = package.path
     package.path = package.path .. ";" .. gPath .. file .. ".lua"
     require(file)
     package.path = prev_path
 end
 
 load_file("slides_utils")
 
 gSlides = parse_file(io.open("/skia/trunk/resources/slides_content2.lua", "r"))
 
 function make_rect(l, t, r, b)
     return { left = l, top = t, right = r, bottom = b }
 end
 
 function make_paint(typefacename, stylebits, size, color)
     local paint = Sk.newPaint();
     paint:setAntiAlias(true)
     paint:setSubpixelText(true)
     paint:setTypeface(Sk.newTypeface(typefacename, stylebits))
     paint:setTextSize(size)
     paint:setColor(color)
     return paint
 end
 
+function center_rect(sw, sh, dst)
+    local dw = dst.right - dst.left
+    local dh = dst.bottom - dst.top
+
+    local rw, rh
+
+    if sw / sh > dw / dh then
+        rw = dw
+        rh = sh * dw / sw
+    else
+        rh = dh
+        rw = sw * dh / sh
+    end
+
+    local x = dst.left + ((sw - rw) / 2)
+    local y = dst.top  + ((sh - rh) / 2)
+    return make_rect(x, y, x + rw, y + rh)
+end
+
+function draw_image_centered(canvas, image)
+    local sw = image:width()
+    local sh = image:height()
+    local dstR = center_rect(image:width(), image:height(), make_rect(20, 20, 620, 460))
+    canvas:drawImageRect(image, nil, dstR)
+end
+
 function draw_bullet(canvas, x, y, paint, indent)
     if 0 == indent then
         return
     end
     local ps = paint:getTextSize()
     local cx = x - ps * .8
     local cy = y - ps * .4
     local radius = ps * .2
     canvas:drawCircle(cx, cy, radius, paint)
 end
 
 function stroke_rect(canvas, rect, color)
     local paint = Sk.newPaint()
     paint:setStroke(true);
     paint:setColor(color)
     canvas:drawRect(rect, paint)
 end
 
 function drawSlide(canvas, slide, master_template)
-    template = master_template.slide   -- need to sniff the slide to know if we're title or slide
+
+    if #slide == 1 then
+        template = master_template.title
+        canvas:drawText(slide[1].text, 320, 240, template[1])
+        return
+    end
+
+    template = master_template.slide
 
     local x = template.margin_x
     local y = template.margin_y
     local scale = 1.25
 
     if slide.blockstyle == "code" then
         local paint = master_template.codePaint
         local fm = paint:getFontMetrics()
         local height = #slide * (fm.descent - fm.ascent)
         y = (480 - height) / 2
@@ skipping 106 matching lines @@
             canvas:translate(x, y)
             drawSlide(canvas, self.slide, gTemplate)
             canvas:restore()
         end
     }
 end
 
 function next_slide()
     local prev = gSlides[gSlideIndex]
 
-    gSlideIndex = gSlideIndex + 1
-    if gSlideIndex > #gSlides then
-        gSlideIndex = 1
+    if gSlideIndex < #gSlides then
+        gSlideIndex = gSlideIndex + 1
+        spawn_transition(prev, gSlides[gSlideIndex], true)
     end
-
-    spawn_transition(prev, gSlides[gSlideIndex], true)
 end
 
 function prev_slide()
     local prev = gSlides[gSlideIndex]
 
-    gSlideIndex = gSlideIndex - 1
-    if gSlideIndex < 1 then
-        gSlideIndex = #gSlides
+    if gSlideIndex > 1 then
+        gSlideIndex = gSlideIndex - 1
+        spawn_transition(prev, gSlides[gSlideIndex], false)
     end
-
-    spawn_transition(prev, gSlides[gSlideIndex], false)
 end
 
 function convert_to_picture_drawable(slide)
     local rec = Sk.newPictureRecorder()
     drawSlide(rec:beginRecording(640, 480), slide, gTemplate)
     return new_drawable_picture(rec:endRecording())
 end
 
 function convert_to_image_drawable(slide)
     local surf = Sk.newRasterSurface(640, 480)
     drawSlide(surf:getCanvas(), slide, gTemplate)
     return new_drawable_image(surf:newImageSnapshot())
 end
 
--- gMakeDrawable = convert_to_picture_drawable
 gMakeDrawable = new_drawable_slide
 
 load_file("slides_transitions")
 
 function spawn_transition(prevSlide, nextSlide, is_forward)
     local transition
     if is_forward then
         transition = gTransitionTable[nextSlide.transition]
     else
         transition = gTransitionTable[prevSlide.transition]
@@ skipping 60 matching lines @@
 end
 
 local bgPaint = nil
 
 function draw_bg(canvas)
     if not bgPaint then
         bgPaint = Sk.newPaint()
         local grad = Sk.newLinearGradient(  0,   0, { a=1, r=0, g=0, b=.3 },
                                           640, 480, { a=1, r=0, g=0, b=.8 })
         bgPaint:setShader(grad)
+        bgPaint:setDither(true)
     end
 
     canvas:drawPaint(bgPaint)
 end
 
 function onDrawContent(canvas, width, height)
     local matrix = Sk.newMatrix()
     matrix:setRectToRect(make_rect(0, 0, 640, 480), make_rect(0, 0, width, height), "center")
     canvas:concat(matrix)
 
@@ skipping 28 matching lines @@
 }
 
 function onCharHandler(uni)
     local proc = keyProcs[uni]
     if proc then
         proc()
         return true
     end
     return false
 end