TweetFollow Us on Twitter

Ports
Volume Number:1
Issue Number:4
Column Tag:C Workshop

Ports

By Chris Derossi

When one thinks of the Macintosh, one of the first things to come to mind is the Mac’s frequent use of windows for multiple, independent areas or objects. Usually, one window is related to one task or concept, and tasks that have very different orientations are in separate windows.

There are several benefits for grouping items or tasks into separate windows. The most important is user interfacing. By using windows, the user can conceptually group similar or common things. This makes the use of sotware more intuitive because the user is shielded from modes in the software. In other words, instead of explicitly needing to have the computer switch to a different mode, all that is needed is to begin operations in a different window.

Obviously, the more intuitive for the user that your software is, the better. Indeed, one of the primary concepts of the Macintosh is that of using tools like icons, the mouse, and windows to decrease the need for special knowledge or special education. In this article, we will take a look at the concept behind windows, that of ports. (In a later article, we will examine windows more closely.)

In order to facilitate the creation of independent windows, the implementation of ports or graph ports provides for completely separate drawing envir- onments. That is, each port is an entire drawing environment, and operations with one port are not related to another.

At any given time, after QuickDraw is initialized, a single port is always active, and is considered the current graph port. QuickDraw operations always occur within the current graph port.

With each graph port are associated several characteristics and parameters. These include location of the port’s bit map, size, clipping region, visible region, background color, and several text mode values. The port’s bit map refers to an area of memory where the bit image of any drawing is put. Usually, this coincides with an area of the screen ram, so that drawing is displayed on the screen. However, this is not a requirement. The port’s bit map can be any area of memory on or off the screen. For example, a port may use an off-screen bit map to prepare an image, then move that image into the screen bit map.

The size of the port is determined by an enclosing rectangle. The rectangle encloses part of the bit map and indicates size and position within the bit map. For ports that are visible, the rectangle encloses an area of the screen.

Clipping region and visible region both restrict the available drawing area within a graph port. While the port itself is rectangular, the clipping and visible areas are regions, providing total flexibility with shape and configuration. The visible region acts like a clipping region, but is separate from it mainly for use by the window manager. (When one window overlaps another, the visible region of the bottom window is set to equal the part of the port that still shows.) There are two regions so that the user may have a region for clipping that is unrelated to the the region needed by the window manager for handling overlap.

Each port is its own drawing environment, and as such has its own drawing characteristics such as pen size, pattern, position, etc. Also, each port has its own text drawing characteristics that are used by the font manager. This way, you need only choose which port in which to draw, and the font, style, and text size associated with that port are automatically used.

In addition to having its own locations, size, and modes, each graph port may also have its own coordinate system. That is, regardless of where on the screen the port is displayed, the upper left corner of the port may be any coordinate. Usually, of course, the upper left coordinate is assigned the value 0,0. This is useful because neither the user nor the programmer need be concerned with the actual position of any port; drawing may be made as if the port were the entire universe. (You might begin to see why moving windows around is so easy; the coordinates inside the window remain constant.)

Since the available coordinate plane is much larger than any visible graph port, this feature allows ports to ‘look at’ different areas of the coordinate plane. For example, a program may draw on the entire plane, and different graph ports may be created as neccessary to view separate parts of the entire area. This can be done without the need for conversions either in the drawing or the displaying; QuickDraw handles all conversions.

There are two important programming practices to develop with regards to ports. The first has already been mentioned; it is a good idea to group similar things, and separate dissimilar things. The second idea is that of port independence. Programs should be written to not rely on any port size or location. (When changing the size of a window, for instance, the program should NOT need a certain size window to perform.)

The sample program this month illustrates the second concept, as the first one is much easier to practice. In this program, the user ‘creates’ television sets on which drawing is displayed. While drawing is occurring, the user may create more TVs, or change which one is active. All this is done by clicking the mouse. If the mouse is clicked in a TV, it becomes the active one, if not, a new TV is created.

Each TV, of course, is a graph port. A port is created, and then in that port a television is drawn. Then, the clipping region of that port is restricted to the ‘picture tube’ part of the picture.

Drawing continues, regardless of which port is active, or where it is. The placement of the port, and the selection of the current port is entirely up to the user. Notice, that the main drawing procedure has absolutely no idea which port is active.

In order to avoid running out of memory, the number of possible ports is restricted. You may vary the constant ‘MaxPorts’ as you like. An array is set up called ‘Screens’ which contains pointers to the graph ports. QuickDraw procedures and functions that act upon ports take a pointer to the port as the parameter, not the port itself. The port is left to be dynamically allocated for flexibility. The type ‘GrafPtr’ is the predefined pointer to a graph port.

The variable ScrnCnt keeps track of how many ports we have created. Since we want to draw only on our TV screens, drawing does not occur if the user has not created any ports yet. When the user clicks the mouse, the program checks to see if the position of the mouse is inside any graph port. The point must first be brought to global coordinates, which makes it independent of any port. Then, one by one, the point is referenced to each graph port and checked against that port’s rectangle. If the point is inside the rectangle, that port is selected as the current one.

When the point lies outside all ports, a new port is created. (Unless all possible ports have been created already; then the program terminates.) The port is initialized and its characteristics are set. Then, the TV is drawn in the port, and the clipping region set. The new port is also set as the current port. Notice that the program explicitly sets the port’s origin. Try playing with the origin values.

When the program ends, it closes each port one by one and frees the memory used by the ports. Then, it creates another temporary port that covers the entire screen. (The default values for the size and location of the port coincide with the screen.) This port is then filled with gray to eliminate the other graphics. Finally, this temporary port is also closed and its memory freed.

Although this is a simple example, it demonstrates a very powerful principle; that of independence. The more independent you programs are, the more flexible they are, and the more control the user may have. This avoids placing pointless limitations on your programs and their users. In addition, programming of this nature helps keep programs functional when the environment changes. (Like moving from a Mac to the Lisa with MacWorks, or future, improved machines.)

This concludes our introduction to the basics of QuickDraw. With this foundation, we can move on into the rest of the Macintosh with a strong background. You might want to try and improve on this sample program as an excersize to increase your skill. For example, try to allow the user to select the size as well as the location of the port. Or, try to prevent the ports from overlapping. If you’re really enthusiastic, have all the TV sets going at once, and let the user change ‘channels’ on each of them, causing different graphics to appear on each channel.

In the next issue, we’ll extend the discussion of ports to windows. We’ll find out what the concept of windows adds to the already powerful idea of ports, and find out what features are provided to the user through the use of windows. Ciao.

program Ports_Demo;

{ Ports_Demo - for MacTutor}
{ -- by Chris Derossi}

 uses
  QuickDraw2;  {QuickDraw2 contains the stuff for regions.}

 const
  MaxScreens = 8;

 type
  TVList = array[1..MaxScreens] of GrafPtr;

 var
  Screens : TVList;
  ScrnCnt : INTEGER;
  done : BOOLEAN;

 procedure SetUp;

 begin
  HideAll;
  ScrnCnt := 0;
  done := FALSE;
 end;

 procedure ShutDown;

  var
   TempPort : GrafPtr;

 begin
  while ScrnCnt > 0 do
   begin
    ClosePort(Screens[ScrnCnt]);
    Dispose(Screens[ScrnCnt]);
    ScrnCnt := ScrnCnt - 1;
   end;

{ Create a new port and fill the screen with gray. }
  NEW(TempPort);
  OpenPort(TempPort);
  BackPat(Gray);
  EraseRect(TempPort^.PortRect);
  ClosePort(TempPort);
  Dispose(TempPort);
 end;

 function MakeTV (Left, Top : INTEGER) : GrafPtr;

  var
   TempPtr : GrafPtr;
   WorkRect : Rect;

 begin
{ Create a new port and set its characteristics. }
  NEW(TempPtr);
  OpenPort(TempPtr);
  PortSize(100, 80);
  MovePortTo(Left, Top);
  SetOrigin(0, 0);

{ Clear the port to white and draw our ‘television’ }
  BackPat(White);
  EraseRect(TempPtr^.PortRect);
  FrameRect(TempPtr^.PortRect);
  MoveTo(80, 0);
  LineTo(80, 80);
  SetRect(WorkRect, 85, 10, 95, 20);
  FrameOval(WorkRect);
  SetRect(WorkRect, 85, 30, 95, 40);
  FrameOval(WorkRect);

{ Restrict the clipping region to the TV ‘screen’ }
  WorkRect := TempPtr^.PortRect;
  WorkRect.right := WorkRect.Right - 20;
  InsetRect(WorkRect, 1, 1);
  ClipRect(WorkRect);
  MakeTV := TempPtr;
 end;

 procedure SetTV;

{ If the mouse is in one of our ports, select that port. If all}
{possible ports are created and the mouse is not in any port,}
{then we’re done. Otherwise, create a new port.}

  var
   MousePt, Pnt1 : Point;
   I, X, Y : INTEGER;
   TempPtr : GrafPtr;

 begin
  TempPtr := nil;
  GetMouse(X, Y); { Current port’s local coordinates }
  repeat { nothing }
  until not Button;

{ Convert to a point, the to global coordinates }
  MousePt.h := X;
  MousePt.v := Y;
  LocalToGlobal(MousePt);
  Pnt1 := MousePt;

{ Scan the existing ports. }
  if ScrnCnt > 0 then { we have some ports to scan }
   for I := 1 to ScrnCnt do
    begin
    SetPort(Screens[I]);
    MousePt := Pnt1;
    GlobalToLocal(MousePt);
    if PtInRect(MousePt, Screens[I]^.PortRect) then
    TempPtr := Screens[I];
    end; { for loop }

  if TempPtr <> nil then { the mouse is in a port; set it }
   SetPort(TempPtr)
  else if ScrnCnt = MaxScreens then { all ports used }
   done := TRUE
  else
   begin
    ScrnCnt := ScrnCnt + 1;
    Screens[ScrnCnt] := MakeTV(Pnt1.h, Pnt1.v);
   end;
 end;

 procedure MainLoop;

  var
   Figure : INTEGER;
   WorkRect : Rect;

 begin
  if Button then
   SetTV;

  if ScrnCnt > 0 then { do some drawing }
   begin
    if random mod 100 < 5 then { Clear the ‘screen’ }
    begin
    SetRect(WorkRect, 0, 0, 90, 90);
    EraseRect(WorkRect);
    end;

{ Create a random rectangle for drawing }
    WorkRect.top := random mod 80;
    WorkRect.left := random mod 80;
    WorkRect.right := WorkRect.left + (random mod 60);
    WorkRect.bottom := WorkRect.top + (random mod 60);
    Figure := random mod 6;
    case Figure of
    0 : 
    FrameRect(WorkRect);
    1 : 
    FrameRoundRect(WorkRect, 18, 18);
    2 : 
    FrameOval(WorkRect);
    3 : 
    PaintRect(WorkRect);
    4 : 
    PaintRoundRect(WorkRect, 18, 18);
    5 : 
    PaintOval(WorkRect);
    end;
   end;
 end;

begin   { Ports_Demo }
 SetUp;
 while not done do
  MainLoop;
 ShutDown;
end.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

WALTR 2 2.0.9 - $39.95
WALTR 2 helps you wirelessly drag-and-drop any music, ringtones, videos, PDF, and ePub files onto your iPhone, iPad, or iPod without iTunes. It is the second major version of Softorino's critically-... Read more
Paperless 2.3.9 - $49.95
Paperless is a digital documents manager. Remember when everyone talked about how we would soon be a paperless society? Now it seems like we use paper more than ever. Let's face it - we need and we... Read more
Adobe After Effects CC 2017 14.1 - Creat...
After Effects CC 2017 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous After Effects customer). The new, more connected After Effects CC... Read more
Adobe Premiere Pro CC 2017 11.0.2 - Digi...
Premiere Pro CC 2017 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Premiere Pro customer). Adobe Premiere Pro CC 2017 lets you edit... Read more
ExpanDrive 5.4.4 - Access cloud storage...
ExpanDrive builds cloud storage in every application, acts just like a USB drive plugged into your Mac. With ExpanDrive, you can securely access any remote file server directly from the Finder or... Read more
Apple Final Cut Pro X 10.3.1 - Professio...
Apple Final Cut Pro X is a professional video editing solution.Completely redesigned from the ground up, Final Cut Pro adds extraordinary speed, quality, and flexibility to every part of the post-... Read more
Apple GarageBand 10.1.5 - Complete recor...
The new GarageBand is a whole music creation studio right inside your Mac -- complete with keyboard, synths, orchestral and percussion instruments, presets for guitar and voice, an entirely... Read more
Yummy FTP Pro 1.11.14 - $29.99
Yummy FTP Pro is an advanced Mac file transfer app which provides a full-featured professional toolkit combined with blazing speeds and impeccable reliability, so whether you want to transfer a few... Read more
Apple Compressor 4.3.1 - Adds power and...
Compressor adds power and flexibility to Final Cut Pro X export. Customize output settings, work faster with distributed encoding, and tap into a comprehensive set of delivery features. Features... Read more
Apple Motion 5.3.1 - Create and customiz...
Apple Motion is designed for video editors, Motion 5 lets you customize Final Cut Pro titles, transitions, and effects. Or create your own dazzling animations in 2D or 3D space, with real-time... Read more

Super Mario Run dashes onto Android in M...
Super Mario Run was one of the biggest mobile launches in 2016 before it was met with a lukewarm response by many. While the game itself plays a treat, it's pretty hard to swallow the steep price for the full game. With that said, Android users... | Read more »
WarFriends Beginner's Guide: How to...
Chillingo's new game, WarFriends, is finally available world wide, and so far it's a refreshing change from common mobile game trends. The game's a mix of tower defense, third person shooter, and collectible card game. There's a lot to unpack here... | Read more »
Super Gridland (Entertainment)
Super Gridland 1.0 Device: iOS Universal Category: Entertainment Price: $1.99, Version: 1.0 (iTunes) Description: Match. Build. Survive. "exquisitely tuned" - Rock Paper Shotgun No in-app purches, and no ads! | Read more »
Red's Kingdom (Games)
Red's Kingdom 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: Mad King Mac has kidnapped your father and stolen your golden nut! Solve puzzles and battle goons as you explore and battle your... | Read more »
Turbo League Guide: How to tame the cont...
| Read more »
Fire Emblem: Heroes coming to Google Pla...
Nintendo gave us our first look at Fire Emblem: Heroes, the upcoming mobile Fire Emblem game the company hinted at last year. Revealed at the Fire Emblem Direct event held today, the game will condense the series' tactical RPG combat into bite-... | Read more »
ReSlice (Music)
ReSlice 1.0 Device: iOS Universal Category: Music Price: $9.99, Version: 1.0 (iTunes) Description: Audio Slice Machine Slice your audio samples with ReSlice and create flexible musical atoms which can be triggered by MIDI notes or... | Read more »
Stickman Surfer rides in with the tide t...
Stickson is back and this time he's taken up yet another extreme sport - surfing. Stickman Surfer is out this Thursday on both iOS and Android, so if you've been following the other Stickman adventures, you might be interested in picking this one... | Read more »
Z-Exemplar (Games)
Z-Exemplar 1.4 Device: iOS Universal Category: Games Price: $3.99, Version: 1.4 (iTunes) Description: | Read more »
5 dastardly difficult roguelikes like th...
Edmund McMillen's popular roguelike creation The Binding of Isaac: Rebirth has finally crawled onto mobile devices. It's a grotesque dual-stick shooter that tosses you into an endless, procedurally generated basement as you, the pitiable Isaac,... | Read more »

Price Scanner via MacPrices.net

Apple Ranked ‘Most Intimate Brand’
The top ranked ‘”intimate” brands continued to outperform the S&P and Fortune 500 indices in revenue and profit over the past 10 years, according to MBLM’s Brand Intimacy 2017 Report, the largest... Read more
B-Eng introduces SSD Health Check for Mac OS
Fehraltorf, Switzerland based independant Swiss company- B-Eng has announced the release and immediate availability of SSD Health Check 1.0, the company’s new hard drive utility for Mac OS X. As the... Read more
Apple’s Education discount saves up to $300 o...
Purchase a new Mac or iPad using Apple’s Education Store and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free: -... Read more
4-core 3.7GHz Mac Pro on sale for $2290, save...
Guitar Center has the 3.7GHz 4-core Mac Pro (MD253LL/A) on sale for $2289.97 including free shipping or free local store pickup (if available). Their price is a $710 savings over standard MSRP for... Read more
128GB Apple iPad Air 2, refurbished, availabl...
Apple has Certified Refurbished 128GB iPad Air 2s WiFis available for $419 including free shipping. That’s an $80 savings over standard MSRP for this model. A standard Apple one-year warranty is... Read more
13-inch 2.7GHz Retina MacBook Pro on sale for...
B&H Photo has the 2015 13″ 2.7GHz/128GB Retina Apple MacBook Pro on sale for $100 off MSRP. Shipping is free, and B&H charges NY tax only: - 13″ 2.7GHz/128GB Retina MacBook Pro (MF839LL/A): $... Read more
Laptop Market – Flight To Quality? – The ‘Boo...
Preliminary quarterly PC shipments data released by Gartner Inc. last week reveal an interesting disparity between sales performance of major name PC vendors as opposed to that of less well-known... Read more
IBM and Bell Transform Canadian Enterprise Mo...
IBM and Bell Canada have announced they are joining forces to offer IBM MobileFirst for iOS market-ready enterprise applications for iPad, iPhone or Apple Watch. Bell, Canada’s largest communications... Read more
Otter Products is Closing… For a Day of Givin...
On Thursday, Feb. 9, Otter Products is closing doors to open hearts. In partnership with the OtterCares Foundation, the company is pausing operations for a day so all employees can volunteer with... Read more
15-inch 2.2GHz Retina MacBook Pro on sale for...
Amazon has 2015 15″ 2.2GHz Retina MacBook Pros (MJLQ2LL/A) available for $1799.99 including free shipping. Apple charges $1999 for this model, so Amazon’s price is represents a $200 savings. Read more

Jobs Board

Intermediate *Apple* macOS Systems Integrat...
**Position Summary:** SC3 is actively seeking an Intermediate Apple macOS systems integration administrator that will be responsible for providing Apple Mac Read more
*Apple* & PC Desktop Support Technician...
Apple & PC Desktop Support Technician job in Los Angeles, CA Introduction: We have immediate job openings for several Desktop Support Technicians with one of our Read more
*Apple* Retail - Multiple Positions - Apple,...
SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Retail - Multiple Positions (Multi-L...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.